Please Please Read this, I Need Some help!!!

I have a problem, I've noticed something that my computer has been doing for sometime now. I have a certain window open, (any window) and I notice that the blue bar at the top of it gets pail. You know in Windows XP the bar is bright blue when the window is in use but if you click outside the window say on the taskbar then it turns a pail blue which indicates that the window is no longer in the foreground. Well i've noticed that whenever i'm using a certain window, it suddenly falls i guess into the background instead of remaining in the foreground. So like i'm typing (and i can't type without looking down at the keys) it happens without me noticing because i'm looking down and when i think i've typed a whole sentence and look up, actually i've only typed a few words because when the window is in the background the keys don't register. Then the other day I noticed something else, I started a fullscreen game and it kept minimizing by itself. These problems still persist, do I have a virus or something i scanned with Norton, The Cleaner Proffesional, Spysweeper, and Ad-Aware to no avail. Hope someone can help me!