In device manager, under Display Adapters, is it showing your ATI card correctly? If so, when you right click it and select properties, what driver
is it showing?
I've used ATI cards for years, and from time to time a new version will be borked up. I haven't downloaded this latest one yet so I don't know if it's got problems.
A possibility is when you select properties, then check "Roll Back Driver" and see if it will take you to the one you were last using. Unless you use the Catalyst Control Center, you could just download the driver itself and try installing that.
When I'm installing new versions I don't remove the display adapter or drivers
. I run Driver Sweeper, as you did, then run the new download.