This happens with the latest and previous releases of the Catalyst/fglrx drivers with Fedora 8 (kernel 2.6.26)
When I quit Nexuiz, the screen darkens slightly and appears to hang. I need to Ctrl+Alt+F1 into a console and kill nexuiz from there (signal 15). Then the colsole goes bonkers, and I don't mean text spew like when you cat /dev/random, but flashing sets of corrupt glyphs. BUT, it's not a total hang as everything works again when I Ctrl+Alt+F7 back into X.
Trying to kill Nexuiz from the colsole (sending it signal 15 twice) without trying to quit from within Nexuiz causes a hard hang that needs a reset.
Is this the same ATI bug that the SVN workaround addresses?