Comment 18 for bug 368461

In my experience I've see tree types of freeze:
(1) system freeze, the screen propose the last seeing, the mouse can move, pc don't respond with keyboad, ssh on (and safely reboot). This behaviour is related to bug #351990
(2) the screen become black and the pc don't respond at all: no mouse, no keyboard, no ssh (hard reboot). This is related to bug this bug
(3) just a crash of kdm. Then I can login into kdm-login-interface and the pc is up. As I've reported before, on kdm.log I've found this backtrace:
*** glibc detected *** /usr/bin/X: realloc(): invalid pointer: 0x0c2b29e0 ***
======= Backtrace: =========
/lib/tls/i686/cmov/libc.so.6[0xb7c94604]
/lib/tls/i686/cmov/libc.so.6(realloc+0x242)[0xb7c99022]
/usr/bin/X(Xrealloc+0x32)[0x8139182]
/usr/bin/X(dixAllocatePrivate+0x103)[0x8072d23]
/usr/bin/X(dixLookupPrivateAddr+0x44)[0x8072e44]
/usr/bin/X[0x817f61f]
/usr/lib/xorg/modules/extensions//libextmod.so[0xb7a04018]
/usr/bin/X(dixDestroyPixmap+0x15)[0x8086d35]
/usr/bin/X(FreeResource+0x10c)[0x8074c3c]
/usr/bin/X(ProcFreePixmap+0x93)[0x8088663]
/usr/bin/X(Dispatch+0x33f)[0x808d57f]
/usr/bin/X(main+0x3bd)[0x80722ed]
/lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe5)[0xb7c3b775]
/usr/bin/X[0x80717a1]
======= Memory map: ========
[.....................]

Yesterday I've update my ubuntu with the last updates. I don't see nothing bugfix that could be related to this bug, but at this moment I've no more crash.