So I've been banging my head on this issue for the past few days, and have come to the conclusion that this is a bug. Hopefully someone knows a workaround.
x64 Intel Sandy Bridge CPU
2 x ATI 6950
4 monitors, all connected to one video card
When I start X either off the LiveCD or installed, I can only have one window open at a time that is usable. If I open a terminal, I can't use any of the Gnome context menus outside of this window to start any other applications. If I exit the terminal, I can then access the context menus to start another application (i.e. firefox). When that application is open, I can type in it, sometimes resize or move the window (usually not), but I can not interact with any other open windows. If I click on another window, nothing usually happends. If I close firefox, I can then access the next window. If a prompt pops up in firefox, I can not click on it, and it clicks behind the prompt. This problem is random and sometimes I can open more than one window at once before it occures. One time I was able to focus on different windows, but everything I typed would go back to the same single window.
I have installed both the generic AMD and Ubuntu built drivers with the same affect. I've tried version 12.8 and 12.10. Keep in mind that this happens before any drivers are installed, but I figured it was worth mentioning. I can't see anything in any logs that would indicate a problem. My setup isn't that unique, so I would be surprised if I was alone in this. This is definitely an odd issue.