If I were you I would first try reinstalling your ATI drivers and direct-X. If it's still the same try that card in another PC if at all possible and if it's ok on that PC then you may have an issue in with your Dell. The card could be overheating. Open up the case (carefully) and turn on your PC and make sure your fan on the card is actually spinning (look with a flashlight to be sure). You may end up having a bad card - hope not. I have had that happen to some of my customers and if the card is in warranty - after trying several solutions to see if it's the card or something within the system i have had to RMA a graphics card for them (I warrant the systems i build) or if th card is out of warranty i have been able to fix a few with your issue by removing the GPU fan and cleaning the GPU chip and re-applying thermal grease and re-attaching the fan (after cleaning the dust out of it). It looks like you may have the memory on the card going bad though. Hope not .