New here

Hey guys. I just joined the community this evening. It seems like a cool community to read. Of course I didn't come unprepared. I actually have a software question that's been bugging me lately. I have an 64mb ddr ATI Radeon 7500 video card. I recently downloaded the new driver for it. I thought it was running ok. I get into a game of Counter-Strike. I alt-tab. Things go smooth. I alt-tab back in and the display turns into something like a mosaic painting. I'm not sure why it's doing that. It doesn't do it all the time, though; I'd say a good 90% of it. I can't figure out a solution other than to re-install the old driver. I haven't tried it with any other games/applications. Suggestions?

(Note: It isn't vital I figure it out. I don't mind using old drivers. It's more of a curiosity thing than anything.)

Peace