Backtrace:
0: /usr/bin/Xorg(xf86SigHandler+0x84) [0x80cfa14]
1: [0xb7f7b420]
2: /usr/lib/xorg/modules/extensions/libGLcore.so(XMesaMakeCurrent2+0x5a) [0xb621b8ba]
3: /usr/lib/xorg/modules/extensions/libGLcore.so [0xb621a3c4]
4: /usr/lib/xorg/modules/extensions/libglx.so(DoMakeCurrent+0x3bc) [0xb7c572cc]
5: /usr/lib/xorg/modules/extensions/libglx.so(__glXMakeCurrent+0x39) [0xb7c57479]
6: /usr/lib/xorg/modules/extensions/libglx.so [0xb7c5a37a]
7: /usr/bin/Xorg(Dispatch+0x19b) [0x8086d4b]
8: /usr/bin/Xorg(main+0x489) [0x806e739]
9: /lib/libc.so.6(__libc_start_main+0xd8) [0xb7cff838]
10: /usr/bin/Xorg(FontFileCompleteXLFD+0xa5) [0x806da71]

Fatal server error:
Caught signal 11.  Server aborting

X connection to :94.0 broken (explicit kill or server shutdown).