Slightly different black screen issue with Trinity.

I can load the game.  I can play, but sometimes it's for five minutes, other times it's for a few hours.  It always ends in my screens going black, then going to standby mode.  The keyboard is unresponsive.  I can't ctrl+alt+del out.  My only option is the reset button on my tower.  No dump file is created.

System specs:

Win 7 64bit SP1

AMD Phenom II x4 3.0GHz

8 GB DDR3 Ram

ASUSTek M5A88-V EVO mobo

ATI Radeon HD 4600 1GB

I am running the game through Steam.

Any assistance would be appreciated.  Thank You.