ARM VFP state can be corrupted during VFP exception handling when PREEMPT is enabled, it appears to occur during VFP exception handling when a task causes a VFP exception which is handled via VFP_bounce and is then preempted by yet another task which in turn causes yet another VFP exception. So to prevent this problem preemption is disabled while handling VFP exceptions.
Got it from omap branch git, committed on 1 apr 2009
From the time I've been testing it, I'd say it fixes completely the shutdown issue.