Binary package hint: compiz
After getting my new Dell Inspiron 531 with an Radeon HD 2600 XT I installed Ubuntu 8.04. Al applications using OpenGL didn't work, gave flickering screens or just froze the whole machine. I had this problem on my previous machine with an NVidia card but with a lot of hassle this could be solved, after every new install. So no games, not even TuxRacer, no GoogleEarth, not even glxgears working properly.
At first I thought there was no direct rendering, given the answer of glxinfo | grep direct "No". In the end I found that this was caused by running a terminal window with a shortcut key. Running a terminal window from the menu gave the correct answer. This bug is reported, I think.
Then after a while I found a thread saying that glrx didn't work with compiz, so with Appearance, Visual effect I clicked "No" and immediately after that everything worked fine.
I also found that Tuxracer gave no sound when started from the menu, and worked well with sound when started in a terminal window, as did some other games. I had this problem as well on my old machine and in that case it was also caused by the graphics.
So in the end it's not too bad, but I liked compiz...
My question now is: Is this a compiz or an fglrx problem?
I'm having the same problem with my Radeon 9600. Compiz features work fine, but 3D rendering has serious issues with Visual Effects active. I do not have this problem with Gutsy Gibbon on the same hardware.