Linux Step By Steps
Freeze Recovery   
From: "David A. Bandel" <>

Next time something like this happens (hard freeze), try this key  sequence:

<Alt><SysRq>u (twice)
<Alt><SysRq>s (3 x)

Your system should reboot and come up without needing an fsck.

Marcus Meissner <>

You however need to do:

   echo -n 1 > /proc/sys/kernel/sysrq

somewhere in your bootup scripts, since it is (runtime) disabled by default.