Blank screen after windows loads

Hello,
I have a new computer, with windows vista 32 bit. Have a gtx 8800 . Windows loads then screen goes black. If i uplug monitor from computer then plug it right back in it works. I can only get 800x600 out of my card which is crazy. If i uninstall drivers everything works fine, but can't get the resolution i want. I've tried every simple fix and get the same problem . My graphics card is 7 months old and i never pushed it hard. Only played halo 2 on it like 50 times !!! What the hell is wrong with this damn 300 Dollar graphics card. My uncle sent me a asus 8500gt and i've had it for 3 months and now it's doing the same thing... on a new computer.. What the hell is going on are these cards dien cause i'm not cleaning out my computer case every month?????