Since I swapped over to windows 7 (64 bit) I have had major technical issues while playing this game - most of the time my screen will freeze, proceed to go blank then come back up with the little bubble "display adapter has stopped responding and recovered successfully". sometimes the client window is pitch-black and to recover it I have to restart the game, sometimes it is fine. There are also times when it freezes, goes blank then my entire system crashes. To remedy this I have tried several different drivers, including the one from manufacturers website, ATI's website, and the one through windows update. here's my rig's specs:

gigabyte GA-MA790FX-DS5 motherboard
AMD phenom II 940 processor
gigabyte HD 4890 graphics card

I have also reformatted and reinstalled windows several times, and narrowed it down to a driver reason after doing the following tests:
-swapped card for a cheap 80 dollar NVIDIA GT8500 card that plays the game fine. card starts to drag if i crank all the settings up though.
-swapped card for identical card (I bought two of the 4890's to put in crossfire mode but took one out since DDO doesnt support crossfire) and have exact same issue.

any suggestions? i have the screen freezing issue seemingly no matter what settings I have the graphics set to, and directx9 or 10 mode doesn't affect it either.