Hi!
I have over the past month received 276 000 000 packets, and sent about the same number over my internet-connection.
This seems to me to be in the extreme, as I have hardly done any filesharing.
I have run all sorts of virus- and malware-scans, and the PC gets a clean bill of health.

Here's a Highjack this log, if anyone is able to read anything abnormal out of it, and give me a tip as to what to do.

Thanks - Nils
Logfile of HijackThis v1.99.1
Scan saved at 10:46:46, on 25.03.2008
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16608)

Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\Programfiler\Fellesfiler\LogiShrd\Bluetooth\LBTServ.exe
C:\Programfiler\Fellesfiler\Symantec Shared\ccSvcHst.exe
C:\Programfiler\Lavasoft\Ad-Aware 2007\aawservice.exe
C:\Programfiler\Alwil Software\Avast4\aswUpdSv.exe
C:\Programfiler\Alwil Software\Avast4\ashServ.exe
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\system32\brss01a.exe
C:\Programfiler\Adobe\Photoshop Elements 5.0\PhotoshopElementsFileAgent.exe
C:\Programfiler\APC\APC PowerChute Personal Edition\mainserv.exe
C:\Programfiler\Fellesfiler\Apple\Mobile Device Support\bin\AppleMobileDeviceService.exe
C:\Programfiler\Bonjour\mDNSResponder.exe
C:\WINDOWS\system32\nvsvc32.exe
C:\WINDOWS\system32\svchost.exe
C:\PROGRA~1\SPEEDB~1\VideoAcceleratorService.exe
C:\WINDOWS\system32\SearchIndexer.exe
C:\Programfiler\Windows Home Server\WHSConnector.exe
C:\Programfiler\Canon\CAL\CALMAIN.exe
C:\Programfiler\Alwil Software\Avast4\ashMaiSv.exe
C:\Programfiler\Alwil Software\Avast4\ashWebSv.exe
C:\WINDOWS\Explorer.EXE
C:\PROGRA~1\SPEEDB~1\VideoAcceleratorEngine.exe
C:\Programfiler\Fellesfiler\Symantec Shared\ccApp.exe
C:\Programfiler\LapBack\lapback.exe
C:\WINDOWS\system32\RUNDLL32.EXE
C:\Programfiler\iTunes\iTunesHelper.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\Programfiler\APC\APC PowerChute Personal Edition\apcsystray.exe
C:\Programfiler\winkey\WinKey.exe
C:\Programfiler\iPod\bin\iPodService.exe
C:\WINDOWS\Installer\{21E49794-7C13-4E84-8659-55BD378267D5}\WHSTRA~1.EXE
C:\Programfiler\Windows Desktop Search\WindowsSearch.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Programfiler\SpeedBit Video Accelerator\VIDEOA~2.EXE
C:\Programfiler\Skype\Phone\Skype.exe
C:\Programfiler\Skype\Plugin Manager\skypePM.exe
C:\Programfiler\Microsoft Office\Office12\OUTLOOK.EXE
C:\Programfiler\Google\GoogleToolbarNotifier\1.2.1128.5462\GoogleToolbarNotifier.exe
C:\WINDOWS\system32\dllhost.exe
C:\WINDOWS\System32\svchost.exe
C:\Programfiler\Google\Gmail Notifier\gnotify.exe
C:\Programfiler\Windows Live\Messenger\msnmsgr.exe
C:\Programfiler\Windows Live\Messenger\usnsvc.exe
F:\Div ved formatering\CommView\CV.exe
C:\Documents and Settings\Nils\Skrivebord\NettverksProgram\HijackThis.exe
C:\Programfiler\Opera\Opera.exe
C:\Programfiler\Internet Explorer\iexplore.exe
C:\Programfiler\Fellesfiler\Microsoft Shared\Windows Live\WLLoginProxy.exe

R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://go.microsoft.com/fwlink/?LinkId=69157
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://go.microsoft.com/fwlink/?LinkId=54896
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://go.microsoft.com/fwlink/?LinkId=69157
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyOverride = localhost;*.local
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Koblinger
R3 - URLSearchHook: Yahoo! Toolbar - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\Programfiler\Yahoo!\Companion\Installs\cpn\yt.dll
O2 - BHO: &Yahoo! Toolbar Helper - {02478D38-C3F9-4efb-9B51-7695ECA05670} - C:\Programfiler\Yahoo!\Companion\Installs\cpn\yt.dll
O2 - BHO: Adobe PDF Reader Link Helper - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Programfiler\Fellesfiler\Adobe\Acrobat\ActiveX\AcroIEHelper.dll
O2 - BHO: (no name) - {1E8A6170-7264-4D0F-BEAE-D42A53123C75} - C:\Programfiler\Fellesfiler\Symantec Shared\coShared\Browser\1.7\NppBho.dll
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Programfiler\Java\jre1.6.0_05\bin\ssv.dll
O2 - BHO: (no name) - {7E853D72-626A-48EC-A868-BA8D5E23E045} - (no file)
O2 - BHO: Påloggingshjelp for Windows Live - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Programfiler\Fellesfiler\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O2 - BHO: BrowserHelper Class - {9A065C65-4EE7-4DDD-9918-F129089A894A} - C:\Programfiler\Windows Home Server\WHSDeskBands.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - c:\programfiler\google\googletoolbar1.dll
O2 - BHO: Windows Live Toolbar Helper - {BDBD1DAD-C946-4A17-ADC1-64B5B4FF55D0} - C:\Programfiler\Windows Live Toolbar\msntb.dll
O3 - Toolbar: Show Norton Toolbar - {90222687-F593-4738-B738-FBEE9C7B26DF} - C:\Programfiler\Fellesfiler\Symantec Shared\coShared\Browser\1.7\UIBHO.dll
O3 - Toolbar: Easy-WebPrint - {327C2873-E90D-4c37-AA9D-10AC9BABA46C} - C:\Programfiler\Canon\Easy-WebPrint\Toolband.dll
O3 - Toolbar: Home Server Banner - {D73E76A3-F902-45BD-8FC8-95AE8E014671} - C:\Programfiler\Windows Home Server\WHSDeskBands.dll
O3 - Toolbar: &Google - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - c:\programfiler\google\googletoolbar1.dll
O3 - Toolbar: Yahoo! Toolbar - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\Programfiler\Yahoo!\Companion\Installs\cpn\yt.dll
O3 - Toolbar: Windows Live Toolbar - {BDAD1DAD-C946-4A17-ADC1-64B5B4FF55D0} - C:\Programfiler\Windows Live Toolbar\msntb.dll
O4 - HKLM\..\Run: [ccApp] "C:\Programfiler\Fellesfiler\Symantec Shared\ccApp.exe"
O4 - HKLM\..\Run: [Symantec PIF AlertEng] "C:\Programfiler\Fellesfiler\Symantec Shared\PIF\{B8E1DD85-8582-4c61-B58F-2F227FCA9A08}\PIFSvc.exe" /a /m "C:\Programfiler\Fellesfiler\Symantec Shared\PIF\{B8E1DD85-8582-4c61-B58F-2F227FCA9A08}\AlertEng.dll"
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\WINDOWS\system32\NvMcTray.dll,NvTaskbarInit
O4 - HKLM\..\Run: [iTunesHelper] "C:\Programfiler\iTunes\iTunesHelper.exe"
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\RunOnce: [SpeedStartup] C:\Programfiler\Speed Startup\speedstartup.exe runonce
O4 - HKCU\..\Run: [SpeedStartup] C:\Programfiler\Speed Startup\speedstartup.exe bootup
O4 - HKCU\..\Run: [swg] C:\Programfiler\Google\GoogleToolbarNotifier\1.2.1128.5462\GoogleToolbarNotifier.exe
O4 - HKCU\..\Run: [MSMSGS] "C:\Programfiler\Messenger\msmsgs.exe" /background
O4 - HKCU\..\Run: [msnmsgr] "C:\Programfiler\Windows Live\Messenger\msnmsgr.exe" /background
O4 - Global Startup: APC UPS Status.lnk = ?
O8 - Extra context menu item: &Clean Traces - C:\Programfiler\DAP\Privacy Package\dapcleanerie.htm
O8 - Extra context menu item: &Download with &DAP - C:\Programfiler\DAP\dapextie.htm
O8 - Extra context menu item: &Windows Live Search - res://C:\Programfiler\Windows Live Toolbar\msntb.dll/search.htm
O8 - Extra context menu item: Download &all with DAP - C:\Programfiler\DAP\dapextie2.htm
O8 - Extra context menu item: E&ksporter til Microsoft Excel - res://C:\PROGRA~1\MICROS~3\Office12\EXCEL.EXE/3000
O8 - Extra context menu item: Easy-WebPrint Add To Print List - res://C:\Programfiler\Canon\Easy-WebPrint\Resource.dll/RC_AddToList.html
O8 - Extra context menu item: Easy-WebPrint High Speed Print - res://C:\Programfiler\Canon\Easy-WebPrint\Resource.dll/RC_HSPrint.html
O8 - Extra context menu item: Easy-WebPrint Preview - res://C:\Programfiler\Canon\Easy-WebPrint\Resource.dll/RC_Preview.html
O8 - Extra context menu item: Easy-WebPrint Print - res://C:\Programfiler\Canon\Easy-WebPrint\Resource.dll/RC_Print.html
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Programfiler\Java\jre1.6.0_05\bin\ssv.dll
O9 - Extra 'Tools' menuitem: Sun Java Console - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Programfiler\Java\jre1.6.0_05\bin\ssv.dll
O9 - Extra button: Create Mobile Favorite - {2EAF5BB1-070F-11D3-9307-00C04FAE2D4F} - C:\PROGRA~1\MICROS~2\INetRepl.dll
O9 - Extra button: (no name) - {2EAF5BB2-070F-11D3-9307-00C04FAE2D4F} - C:\PROGRA~1\MICROS~2\INetRepl.dll
O9 - Extra 'Tools' menuitem: Opprett mobil favoritt... - {2EAF5BB2-070F-11D3-9307-00C04FAE2D4F} - C:\PROGRA~1\MICROS~2\INetRepl.dll
O9 - Extra button: Research - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~3\Office12\REFIEBAR.DLL
O9 - Extra button: (no name) - {e2e2dd38-d088-4134-82b7-f2ba38496583} - %windir%\Network Diagnostic\xpnetdiag.exe (file missing)
O9 - Extra 'Tools' menuitem: @xpsp3res.dll,-20001 - {e2e2dd38-d088-4134-82b7-f2ba38496583} - %windir%\Network Diagnostic\xpnetdiag.exe (file missing)
O9 - Extra button: Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Programfiler\Messenger\msmsgs.exe
O9 - Extra 'Tools' menuitem: Windows Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Programfiler\Messenger\msmsgs.exe
O9 - Extra button: SmartWhois - {FD9DE2B4-C926-4460-81C4-FC58C6F1062E} - C:\Programfiler\SmartWhois\swmsie.exe
O9 - Extra button: (no name) - {FF983118-58C7-4AD4-B5A7-691C39CB7B42} - C:\Programfiler\SmartWhois\swmsie.exe
O9 - Extra 'Tools' menuitem: SmartWhois - {FF983118-58C7-4AD4-B5A7-691C39CB7B42} - C:\Programfiler\SmartWhois\swmsie.exe
O10 - Unknown file in Winsock LSP: c:\programfiler\bonjour\mdnsnsp.dll
O11 - Options group: [INTERNATIONAL] International*
O16 - DPF: {8AD9C840-044E-11D1-B3E9-00805F499D93} (Java Runtime Environment 1.6.0) - http://sdlc-esd.sun.com/ESD39/.....-windows-i586-jc.cab
O16 - DPF: {D27CDB6E-AE6D-11CF-96B8-444553540000} (Shockwave Flash Object) - http://fpdownload2.macromedia.com/get/shockwave/cabs/flash/swflash.cab
O18 - Protocol: bwfile-8876480 - {9462A756-7B47-47BC-8C80-C34B9B80B32B} - C:\Program Files\Logitech\Desktop Messenger\8876480\Program\GAPlugProtocol-8876480.dll
O18 - Protocol: livecall - {828030A1-22C1-4009-854F-8E305202313F} - C:\PROGRA~1\WI1F86~1\MESSEN~1\MSGRAP~1.DLL
O18 - Protocol: ms-help - {314111C7-A502-11D2-BBCA-00C04F8EC294} - C:\Programfiler\Fellesfiler\Microsoft Shared\Help\hxds.dll
O18 - Protocol: msnim - {828030A1-22C1-4009-854F-8E305202313F} - C:\PROGRA~1\WI1F86~1\MESSEN~1\MSGRAP~1.DLL
O18 - Protocol: skype4com - {FFC8B962-9B40-4DFF-9458-1830C7DD7F5D} - C:\PROGRA~1\FELLES~1\Skype\SKYPE4~1.DLL
O18 - Filter hijack: text/xml - {807563E5-5146-11D5-A672-00B0D022E945} - C:\PROGRA~1\FELLES~1\MICROS~1\OFFICE12\MSOXMLMF.DLL
O20 - Winlogon Notify: LBTWlgn - c:\programfiler\fellesfiler\logishrd\bluetooth\LBTWlgn.dll
O23 - Service: Ad-Aware 2007 Service (aawservice) - Lavasoft - C:\Programfiler\Lavasoft\Ad-Aware 2007\aawservice.exe
O23 - Service: Adobe Active File Monitor V5 (AdobeActiveFileMonitor5.0) - Unknown owner - C:\Programfiler\Adobe\Photoshop Elements 5.0\PhotoshopElementsFileAgent.exe
O23 - Service: APC UPS Service - American Power Conversion Corporation - C:\Programfiler\APC\APC PowerChute Personal Edition\mainserv.exe
O23 - Service: Apple Mobile Device - Apple, Inc. - C:\Programfiler\Fellesfiler\Apple\Mobile Device Support\bin\AppleMobileDeviceService.exe
O23 - Service: avast! iAVS4 Control Service (aswUpdSv) - ALWIL Software - C:\Programfiler\Alwil Software\Avast4\aswUpdSv.exe
O23 - Service: avast! Antivirus - ALWIL Software - C:\Programfiler\Alwil Software\Avast4\ashServ.exe
O23 - Service: avast! Mail Scanner - Unknown owner - C:\Programfiler\Alwil Software\Avast4\ashMaiSv.exe" /service (file missing)
O23 - Service: avast! Web Scanner - Unknown owner - C:\Programfiler\Alwil Software\Avast4\ashWebSv.exe" /service (file missing)
O23 - Service: Bonjour-tjeneste (Bonjour Service) - Apple Inc. - C:\Programfiler\Bonjour\mDNSResponder.exe
O23 - Service: BrSplService (Brother XP spl Service) - brother Industries Ltd - C:\WINDOWS\system32\brsvc01a.exe
O23 - Service: Canon Camera Access Library 8 (CCALib8) - Canon Inc. - C:\Programfiler\Canon\CAL\CALMAIN.exe
O23 - Service: Symantec Event Manager (ccEvtMgr) - Unknown owner - C:\Programfiler\Fellesfiler\Symantec Shared\ccSvcHst.exe" /h ccCommon (file missing)
O23 - Service: Symantec Settings Manager (ccSetMgr) - Unknown owner - C:\Programfiler\Fellesfiler\Symantec Shared\ccSvcHst.exe" /h ccCommon (file missing)
O23 - Service: Symantec Lic NetConnect service (CLTNetCnService) - Unknown owner - C:\Programfiler\Fellesfiler\Symantec Shared\ccSvcHst.exe" /h ccCommon (file missing)
O23 - Service: COM Host (comHost) - Symantec Corporation - C:\Programfiler\Fellesfiler\Symantec Shared\VAScanner\comHost.exe
O23 - Service: Google Updater Service (gusvc) - Google - C:\Programfiler\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: InstallDriver Table Manager (IDriverT) - Macrovision Corporation - C:\Programfiler\Fellesfiler\InstallShield\Driver\1050\Intel 32\IDriverT.exe
O23 - Service: iPod-tjeneste (iPod Service) - Apple Inc. - C:\Programfiler\iPod\bin\iPodService.exe
O23 - Service: Logitech Bluetooth Service (LBTServ) - Logitech, Inc. - C:\Programfiler\Fellesfiler\LogiShrd\Bluetooth\LBTServ.exe
O23 - Service: LiveUpdate - Symantec Corporation - C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
O23 - Service: LiveUpdate Notice Service Ex (LiveUpdate Notice Ex) - Unknown owner - C:\Programfiler\Fellesfiler\Symantec Shared\ccSvcHst.exe" /h ccCommon (file missing)
O23 - Service: LiveUpdate Notice Service - Unknown owner - C:\Programfiler\Fellesfiler\Symantec Shared\PIF\{B8E1DD85-8582-4c61-B58F-2F227FCA9A08}\PIFSvc.exe" /m "C:\Programfiler\Fellesfiler\Symantec Shared\PIF\{B8E1DD85-8582-4c61-B58F-2F227FCA9A08}\PifEng.dll (file missing)
O23 - Service: NBService - Nero AG - C:\Programfiler\Nero\Nero 7\Nero BackItUp\NBService.exe
O23 - Service: NMIndexingService - Nero AG - C:\Programfiler\Fellesfiler\Ahead\Lib\NMIndexingService.exe
O23 - Service: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\system32\nvsvc32.exe
O23 - Service: Symantec Core LC - Symantec Corporation - C:\Programfiler\Fellesfiler\Symantec Shared\CCPD-LC\symlcsvc.exe
O23 - Service: Symantec RemoteAssist - Symantec, Inc. - C:\Programfiler\Fellesfiler\Symantec Shared\Support Controls\ssrc.exe
O23 - Service: VideoAcceleratorService - Speedbit Ltd. - C:\PROGRA~1\SPEEDB~1\VideoAcceleratorService.exe

Sounds like a Botnet using your PC as a Zombie.
If you have free version of DAP try removing it since it contains adware that could cause your symptoms.