I have a lot of problems with the Ati propietary driver (fglrx).
I have an iMac (mid 2011) with a Radeon HD 6900M [1002:6720].
I did not have any problem under Ubuntu 12.04, but since I updated to 12.10, I get some annoying graphic corruption.
The worst one is that sometimes the screen does not update with the new information. It happens a lot when I change between tabs in Chrome or Sublime Text. It usually gets updated when I scroll the page.
Sometimes, when I type, I have to wait a little bit to view the new characters.
And I get trails when I move windows too (like a part of the window). After a while, the trail disappears.
I tried to install fglrx, fglrx-updates and the new beta driver downloaded from Ati (12.11 Beta 11/16/2012), with no luck. It happens the same with all of them.
I tried to mess with Compiz config, but it didn't fix anything.
The open source driver does not suffer this problem, but I need the performance of the propietary driver .
Do you have any clue?