Start menu close/flashes/disappears

I just started having this problem:

1.) Click Start menu.
2.) Mouse to desired program group...
3.) (POOF) watch as your start menu closes.
4.) go back to step 1, repeat as many times as you wish with the same result.

I am almost certain it is related to Internet Explorer 9 which I just installed. I used Sytem Restore to reset my OS into a usable state, re-installed IE9, and the problem is back.

Do you have any ideas?

My machine is a WIn7/AMD Quad Core/4Gigs of RAM/MSI motherboard.
MSE antivirus is the only security I'm running.

Thanks.

It sounds like a process is pulling focus away from what you are doing. Open Task Manager and see if you see any errant processes.

In addition to the suggest scan for malware of course.