Have changed firewall and antivirus apps to COMODO & AVG. Previously  ZA. All working well except when using Mozilla Thunderbird. A dialog pops up asking for my freeserve address password.entering it changes nothing,it just asks for it again & again.Canceling this message then allows normal download of emails?Outlook Express was also effected but is ok now? Have tried reinstalling  Thunderbird &  Freeserve A/C. Cleaned registry with Reg Vac. All to no avail. >:(

   Mailwasher gives me the dialog popup asking for the username and password when there is something wrong with the internet connection.  Usually it is a problem with my router that is not getting the internet to my laptop.  Once I fix the router (usually by turning it off and then back on), it works.
   Maybe something like that is what is happening with you.

Thanks for your helpful reply.  Problem solved be reinstalling image file of Xp and dumping Comodo and AVG.Suspect AVG.