Now that you’ve supplied a few more tidbids of info, I’ll take a shot. You said you used a copy of avast that you had on your desktop. I’m guessing that it was older than 4.7.942 and avast did an auto update. ME and win 98, sometimes have problems with program updates. If this is the case, please see

http://forum.avast.com/index.php?topic=26718.0

You may also want to try to honor VLK’s request contained in the same post. It may help for future updates.