Video Card

I currently have a dell dimension 8400. I was using my pc then it rebooted itself. So now everytime it starts up it goes pass the windows screen and the monitor goes black. So i went to safe mode and tryed to update my nividia 7600 geforce gs drivers.

The drivers will load then the pc will reboot and screen goes black again. I did notice when i looked in device manager it would show unknown device for vga. When i restart it will then find the hardware and the same scernario continues. Anyone have any idea what this could be.