DavidR
3
Well I doubt it has anything to do with the installation of avast and is probably nothing more than a coincidence. However , to have it happen on two system is strange and reduces the coincidence theory. You could uninstall avast on one system and see if it goes away, which I doubt. A clean reinstall as Tech mentions is another option.
If it was a common occurrence (after avast install) we would I’m sure see many posts about it and this is the first I have seen in over three years at the forums. I’ve never experienced it myself with or without avast installed.
A google search brings many hits (though not all seem related) http://www.google.com/search?q=Start+button+flickering.