If your having this problem don't freak out and sledge hammer your pc.."Like I almost did" >.>.... Replace the card, it's bad.. I'm using a 5850 reference model from visiontek. I had the issue whenever I started anything full screen, including but not limited to games, firefox and videos. What does help it if you don't want to revert to old drivers, is a simple reinstall of the driver. I reinstalled dx and the driver and haven't had the problem for a week or so now. I did this before but the problem came back. I'm just waiting for it to rear it's ugly head again and I'll reinstall the drivers again. From ATI: Thank you for your request. Based on the information provided, we understand that you occasionally have noticed no display after you start up my system and go to start Firefox or Steam on a system installed with a VisionTek Radeon HD 5850 PCI-E 1GB. If we have misinterpreted any critical information about your issue, please inform us since our recommendations may be different based on your specific situation. Currently, we have already registered the issue that you have reported, which relates to a possible VBIOS or driver incompatibility with Catalyst 11.6, Windows Timeout Detection and Recovery or a required motherboard chipset driver update. Please revert to your previous Catalyst 11.x or similar until we can address the issue. In the interim, we have forwarded your observations to AMD Technical Support Engineering for further review. In order to confirm your issue, contact the AMD Manufacturer, which is VisionTek for any available VBIOS or driver fixes or updates. NOTE: AMD Manufacturers include as Acer, Apple, ASUS, DELL, Diamond Multimedia, Gigabyte, HIS Digital, HP, Lenovo, PowerColor, Sapphire Technology, SONY, VisionTek, XFX. For documented Windows Timeout Detection and Recovery (TDR) issues, we recommend that you refer to the article provided: Timeout Detection and Recovery of GPUs through WDDM http://msdn.microsoft.com/en-us/windows/hardware/gg487368.aspx The operating system may crash when you run a D3D application full-screen in an immediate mode on Windows 7 or on Windows Server 2008 R2 http://support.microsoft.com/kb/2400157 If you follow the recommendations provided, we believe that you will be able to address and eventually resolve your issue. Please contact us further if your issue is not resolved and we will address and review your issue. Please contact us if you require additional information. If we do not receive a reply from you within 10 days, the Service Request will be closed, and you will need to open a new Service Request if your issue is not yet resolved. Thank you for choosing AMD! NONE OF THIS HELPED SO DON'T BOTHER.