Weird XP problem

[mystvearn]

Last night, WMP9 ask me to update something, so I update it. Its still v9. Something about copyright issues. Then I watched a movie on wmp9, notice that evrey 2,3 minutes, the full screen becomes normal window mode. I make it full screen again, and the problem is still the same. I also notice that my monitor will not go to standby. I set 15 minutes. the blank screen saver kicks in in 2 minutes. After the screen goes blank(screen saver) it suddenly goes back to the desktop. I don't kwno why. Its like something is hitting some keys to make this happen. I used system restore to before wmp update was installed its the same. I used adware, spybot, NAV, nothing.
Help.

[mystvearn]

Since I cannot edit it already, here are more of the same problems affecting other programs.
1. Since wmp9 is irrritating me while I see movies, I switch tto Divx 2.5. Its better, but the problem is still there. Unlike wmp where the screen becomes window mode, the startup bar comes out at the bottom while watching videos. & when this happens, I cannot control divx player using short keys.
2. While typing using the quick reply, suddenly I cannot type. Its like when the mouse is being pressed on the start bar, and the browser(firefox), cannot be used. Its like when you clik on other window, the window you were on becomes useless.
Looks like the problem is universal, & I cannot correct it.
Help