This is my second fresh install on this machine, the previous install also suffered this problem. The machine has been tested with Windows and works perfectly. I ran a single pass of memtest86 and it found no problems. I have removed all PCI cards from the machine, underclocked it, turned off as many features that might increase instability as I could find and there is no change. The error and repeted segfaults from glxgears seem like some kind of library/binary-interface/compiler incompatibility.
I've attached my current XF86Config-4 in case I'm missing something obvious.