Kernel panic after upgrade from FC2t1

[Peter Campion-Bye]

Hi,
I did an 'apt-get dist-upgrade' on my FC2t1 box that was working fine, now
it won't boot. Blue screen at boot time says:

kernel/timer.c:295: spin_lock(kernel/timer.c:0230e3a0) already locked by
kernel/timer.c/392
Kernel panic: Fatal exception in interrupt
In interrupt handler - not syncing

Full screen dump can be seen here: http://www.pandasys.co.uk/panic.jpg

Anyone got any ideas on where I should go from here?
Thanks