Thanks!..now back to topic
lol, have you tried a different card in the system ? Your need to uninstall the old drivers even if the new cards from the same company.
I'd also run memtest86 overnight on the system to see if there's any errors, how ever some times you need to run the test twice to be certain there's no errors.
I myself am in the process of changing out my 4890 with a 4670 to test WMP with my AVIs from fraps, lol I'm hoping its the motherboard that's causing my issues as I'm replacing that and my ram soon lol.