When the X server receives a SIGSEGV and calls FatalError from the signal handler,
a second SIGSEGV from within the handler causes a complete system hang.

Backtrace:
(The first SIGSEGV was generated using a killall -SEGV X from within KDE).

Program received signal SIGSEGV, Segmentation fault.
XkbEnableDisableControls (xkbi=0x8256fc8, change=542, newValues=512, changes=0x0,
    cause=0xbf9b14d4) at xkbUtils.c:748
748         ctrls= xkbi->desc->ctrls;
(gdb) where
#0  XkbEnableDisableControls (xkbi=0x8256fc8, change=542, newValues=512,
    changes=0x0, cause=0xbf9b14d4) at xkbUtils.c:748
#1  0x0818501a in XkbRemoveResourceClient (inDev=0x82503e8, id=1088421888)
    at xkbEvents.c:1014
#2  0x0807e462 in CloseDevice (dev=0x82503e8) at devices.c:512
#3  0x0807e6a9 in CloseDownDevices () at devices.c:530
#4  0x081b18c3 in AbortServer () at log.c:408
#5  0x081b1dd6 in FatalError (f=0x81bc294 "Caught signal %d.  Server aborting\n")
    at log.c:555
#6  0x080bed6d in xf86SigHandler (signo=11) at xf86Events.c:771
#7  <signal handler called>
#8  0xffffe410 in __kernel_vsyscall ()
#9  0xb7d0925d in select () from /lib/i686/libc.so.6
#10 0x081a49f3 in WaitForSomething (pClientsReady=0xbf9b1ba0) at WaitFor.c:238
#11 0x08085e42 in Dispatch () at dispatch.c:425
#12 0x0806d825 in main (argc=8, argv=0xbf9b20d4, envp=0x0) at main.c:467
(gdb)    

A subsequent step causes a complete system hang.