Since updating from 7.5 to 7.6 (Ubuntu 10.10 -> 11.04), X crashes occasionally, maybe 1-3 times per day. According to the backtrace (see below), the crash is in PlayReleasedEvents in dix/events.c.

I've made a variety of changes hoping to avoid the problem, so far without success. These include: changing display drivers, switching to an older Linux kernel that I used before the problem started, trying new Xorg packages from the XorgOnTheEdge repository, switching video cards (ATI and NVIDIA), and even switching architectures from i386 to x86_64.

The crash seems to be related to keyboard input, since it only happens when I'm actively typing - never when I'm not at the system, or just using the mouse.

Here is the backtrace:

#0 0x000000000043d7e5 in PlayReleasedEvents () at ../../dix/events.c:1188
        prev = <value optimized out>
        qe = 0x3096340
        dev = <value optimized out>
        pDev = <value optimized out>
#1 ComputeFreezes () at ../../dix/events.c:1385
        replayDev = <value optimized out>
        w = <value optimized out>
        grab = <value optimized out>
        dev = <value optimized out>
#2 0x000000000043df1b in ProcAllowEvents (client=0x2965480) at ../../dix/events.c:1846
        time = {months = 0, milliseconds = 18270373}
        mouse = 0x2544b90
        keybd = <value optimized out>
        stuff = 0x2f426a0
#3 0x000000000042e2a9 in Dispatch () at ../../dix/dispatch.c:431
        clientReady = 0x26e75d0
        result = <value optimized out>
        client = 0x2965480
        nready = 0
        icheck = 0x7f1410
        start_tick = 5560
#4 0x0000000000421a7e in main (argc=1, argv=<value optimized out>, envp=<value optimized out>) at ../../dix/main.c:287
        i = <value optimized out>
        alwaysCheckForInput = {0, 1}