Screen flashs/blinks and resets open drop-downs

Hi,
Recently my computer screen 'blinks' like a refresh of some sort and if I'm in a program like Quicken or Microsoft Maps with a drop-down menu open, the drop-down will close before I'm finished selecting anything. (very annoying when trying to type something or scolling down a long list).
It doesn't do it on all programs, like IE is fine with no blinks, but Outlook Express blinks.

I have a P4 with 1.5 GB of RAM, running XP Home, multiple IDE HDD's. I've tried going through as many background programs as possible. The 'blinking' (that looks like a screen refresh) is steady at once every 10 seconds, again only on certain programs. Right now typing this in IE 6, it doesn't do it at all. Any of the MS Office programs, including Outlook are fine, but Maps, Outlook Express, Quicken all 'blink'.
I've run anti-virus, anti-spyware and cleaned everything. It's really annoying.
Please help.