ATI RADEON 4850 shuts down after bios screen

Hi everyone,
I just built my 1st system, with some wonderful help from the mates on this forum. My graphics card however shuts off (monitor goes to sleep) when windows starts loading. It is usually fine in the bios screen, as soon as I exit - poof. I have tried reinstalling drivers, other pci-e slots etc. I am relegated to using an old X1300 pro. Any ideas my system is
AMD 4170
Asrock Fatality Pro mobo
8 GB Corsair vengeance
Rosewill 850W power supply
Windows 64 bit
Thanks for your help, and happy Venus transition day.

I have had this problem with Nvidia cards.
It turned out that my screen was incompatible.
If you have a driver or disk for your monitor, install it.

Thanks a lot for your help. I will give that a try when I get home.

Have you tried booting in safe mode?

Hit "F8" repeatedly prior to the windows loading screen.