What version drivers are you running? Catalyst 11.11? Other?
Possible suggestion:
1. uninstall the video driver
2. run a driver cleaner app to really make sure it is gone
3. reinstall
4. Don't trust windows to update the driver. Get it yourself from AMD and install it manually.
Once the BOINC client acknowledges you have a GPU that can crunch, you shouldn't have any problem getting work from Collatz.