I solved this problem.
Apparently there's a conflict with xubuntu 12.10 and AMD catalyst 12.10 or greater.
I had to install xubuntu 12.04 and install catalyst 12.8.
This is extremely helpful... couldn't find a solution for this with xubuntu, so I gave up. Thanks for posting back your results Frozen.
The exact same thing is happeneing to me. Did this fix your problem?