i have a Intel I5 with 8GB RAM and a AMD EAH5770 with 1GB VRAM. Windows 7 Build 7601 is installed. After i start the Game a Window comes on with white Background and the PC is to freeze. Anything goes, it hang up - only reset!
Try the "troubleshoot compatability" option; it's helped others who are having issues with Windows 7. Also, there are some known issues with some AMD cards/drivers/settings; see the "known issues" post. Make sure you aren't using anything exotic like crossfire or eyefinity, and try changing driver versions (either updating to a newer version, or rolling back to an earlier version).