• I'm unable to take screenshots/screengrabs. Everything I try ends up being a blank, black screen, though I can see my cursor.
  • Full-screen video doesn't work in any web browser. I see a blank, black screen, but I can hear the audio.
  • Full-screen games in Steam don't work. I see a blank color, but I can hear the audio.

I have an ATI Radeon HD 6850 (BARTS) and I'm running the latest Catalyst drivers on 12.04 (x64). The OS's GUI seems to be snappy and smooth, nor do I have any other problems. What can I do to fix this?