Apologies, I've realized I'd misunderstood the diverts introduced by xorg-driver-fglrx; the problem is that the libGL in that package doesn't support non-power-of-two textures, and removing it allowed compiz to work fine.
However, compiz ought to work when the fglrx driver is installed but not being used; I've reported that as bug #98940 under compiz. -- libGL.so.1.2 does not support non-power-of-two textures https://launchpad.net/bugs/97631 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs