https://bugs.freedesktop.org/show_bug.cgi?id=81644
--- Comment #23 from jackdachef@gmail.com --- @Aaron:
try reading into Magic SYSRQ key: http://en.wikipedia.org/wiki/Magic_SysRq_key
next time when X seems to freeze - first do a Magic SYSRQ + R, then try to imitate a "secure attention key" == Magic SYSRQ + k
whether that unlocks it
or if X doesn't show any change anymore but the system still seems to be alive:
Magic SYSRQ Key + r
then Magic SYSRQ Key + w (what tasks or kernel threads, etc. is stuck)
then the rest of "REISUB" (Magic SYSRQ Key + e, i, s, u, b)
after the next start you can look through the contents of the kernel messages in
/var/log/kern.log
via
tail -n 3500 /var/log/kern.log | less
(keyboard cursor up & down, quit via "q")
if the messages are too much
try via
tail -n 7500 /var/log/kern.log | less
or higher
sudo may be needed, if not using root privileges
logging may be disabled, so it first might have to be enabled
hope this helps ...