Strange Windows behavior - Start button flickering

[oatpower]

Hello list.

I browsed thru this and other lists + a lot ofa FAQ:s, but could not find a solution, so here goes:

I have a strange problem on two 1 k Celeron / 512 Mb /30 Gb WinXPpro sp2 machines; both machines were installed from scratch with XPpro sp 1, then installed Avast 4.7 Home, the fully patched:
- When fresh booted the text on the Start button flickers rapidly, and pressing it just briefly pops up the menu, then it disappears again.
- Any press on any icon in taskbar renders same result; just a brief menu (or other window) popup
- If task manager is brought up (Ctrl+Alt+Del) the flickering stops, and all menus starts to behave ok
- No signs of viruses, malware, grayware or whatever
- No error messages in system or app logs indicating problems
- All installed programs works ok, except one glitch in Firefox 2.0.0.4; I am unable to customize the toolbar, when trying to drag a new button to it from the cutomization window, the new tool won't stick to cursor and folllow, instead it just flicker once...

Problem seems to appear when, after installing Avast, it after a while annonuced a new version is available, and that one was installed. - And -  NB! Both machines (one HP mini-PC e40 and one Fujitsu-Siemens Scenic) behaves exactly the same... System was installed and patched similarly on both these. No other AV software, spyware removers, etc. is installed, just ordinary programs. Machines are not overclocked or tampered with in any way. The hardware works ok, no driver or similar problems.

Any ideas where to look for a solution?
Have a Good day
Thomas

[Lisandro]

Did you install avast 4.7.1001 from the scratch or did you upgrade from older versions?
Did you try to return back to the old 4.7.986 (http://www.filehippo.com/download_avast_antivirus/)?

Flickering is not an easy problem to debug...

[DavidR]

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.