Dom0 shutdown hangs

Hi,

I have a netbsd dom0 running 2 * netbsd domU and 1 * debian
domU.
Ok so far, but when I execute shutdown -r on *dom0* (or just
reboot)
it just hangs.

On console things look quite normal, I get
syncing disks... done
unmounting file systems...
unmounting /kern
unmounting /opt
unmounting /... done
rebooting....

and then it just hangs. I have to power-cycle the machine.

Any ideas I could try to fix this ? I plan to administer
this server mostly remotely so this is a little bit
annoying...

	Ari S.