I still believe it has something to do with those theme/visual style tweaking utilities you have used in the past...

Yes so do i.

Only thing i could suggest is to update your video card drivers, try to re-install avast! trough add/remove, reboot and run the standard uninstall utility over it, reboot install avast! and see if it works. You could also run the old sfc /scannow command to see if there are any system files needing to be fixed.

And get rid of those visual style utilites if you use the default XP theme … :wink: