Linux Step By Steps
Freeze Recovery   
 
From: "David A. Bandel" <david@pananix.com>


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

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


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


Marcus Meissner <marcus@jet.franken.de>

You however need to do:

   echo -n 1 > /proc/sys/kernel/sysrq

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