On Fedora 8, the new X11 is breaking programs like nmrDraw from NMRPipe. The program runs fine under Fedora 7 but fails under Fedora 8 with the error... nmrdraw: xcb_io.c:285: _XAllocID: Assertion `!(dpy->flags & (1L << 3))' failed. Abort This problem also has been reported for the latest OpenSuse. I found the following thread which sounds like the problem... https://lists.linux-foundation.org/pipermail/lsb-discuss/2007-August/004171.html Unfortunately, it seems that we may need to rebuild X11 to disable some of these new tests. Jack