alanrf, I have tried your suggestion and took all the update from microsoft, including ie 7. Unfortunately, I still can not install avast.
Tech, I can't get Avast to install following your suggestion. It does not even make it to control panel, so setup.ini only contains those 2 lines:
[DownloadSettings]
FailSafeServer=C:\DOCUME~1\Serge\LOCALS~1\Temp\_av_sfx.tm~a02804
[UpdateSummary]
LastErrorMsg=Invalid file signature. Setup will terminate.