I run Windows7 with a 2.5Ghz Intel dual core. I have 2x4650s and 1x6850. ) I've had this setup working for a couple years, and have been updating as time goes by. Usually I can manage to figure out how the driver has decided to break my configuration but this time is different.
I use 3 monitors as single monitors attached to 3 of the 4 ports the 2 4650s give me. The 3 monitors on the 6850 are built into an Eyefinity 1x3 wide display group.
I installed the new catalyst 13.1, and only the 6850 worked. The 4650s come up as "Windows has stopped this device because it has reported problems. (Code 43)". I've uninstalled everything, rebooted, and if I install the Catalyst 12.6, I get all cards working again (4650s on driver 8.920.0.0), but I can't run the Catalyst control panel to reconfigure my Eyefinity group, I get an error that it can't find any AMD graphics cards. So I update just the driver for the 6850 to the 13.1 driver package, and my 4650s are broken again as soon as that driver becomes active on the 6850.
I just want to go back to what was working, and I promise I'll never try to update my drivers again, no matter how often I have to reboot to get rid of artifacting.