I don't know what rockstar is but since you seem to own it remove it for now, completely. Reboot check your settings. Now go to contrl mgr/device mgr/video.
Select your GTS 250 right click, a window should pop up offer choices. It usually starts with update driver, at the bottom of that window is a selection to remove which includes all drivers, select that and remove all of it. Now shut down, get out your gts 250 driver disk, start up windows should see your 250 and hopefully ask for the drivers, follow the prompts and get the card reinstalled , reboot check the card performance. If it's all ok again or finally good. If not then I'd guess theres still something in the registry. You need to fix it at this level before involving the Rockstar program again. by the way what is rockstar? hardware or software?