I started having this problem after I upgraded to Windows 7 x64. I have an ATI 5850 from Sapphire. I have the latest drivers from December, but this problem still keeps happening the weird thing is it only happens when I am browsing and watching any form of video online, and the more videos I que the faster it happens. I tried the various solutions online such as setting my clock speeds 400/900 since my card liked to go down to 157/300 after sleep. The temps arent getting high at all when I am looking inside the CCC during the videos but they also say 0% activity. This display issue also doesnt happen when I play games.
I am beginning to think this is a 64bit issue since I had 32 bit for a while and this card had no problems then