Dear,
I am using avast as antivirus (with windows xp pro)
Regularly I get a small red window with : error, could not actualise..
I go on internet by dial and set my avast:'ask each time tu update'
Thanks
Frans

According to their faq on their web site, the program checks for an internet connection every 40 seconds. If it finds one, it connects to the server for an update. When it updates, it then waits 4 hours before checking again.

The window is telling you it was unable to find the server to check for updates.

The website gives you a way to optimize the program to prevent the check every 40 seconds when using dialup.
See the following page.
http://www.avast.com/eng/updates2.html
See the paragraph about halfway down the page- 3)Optimization for dialup connections.

thanks! I didn't see your answer before
frans