Menu bar and everything except for the game froze.

I start a game, then everything that is not the game doesn't work. I can't move the window, I can't use a menu, I can't minimize, etc. Mouse does work (I can move it), and the keyboard works too.

This happened the same day I put a new video card (GeForce FX 5200), but I was told the problem began before I installed the card.