reboot hangs at Uptime:

I built a 6.0-current yesterday and the system is up and running fine.
Despite of the .depend glitches in /usr/obj requiring me to delete /usr/obj
upon advice from the list here, everything went smooth.

I still have the problem that my machine cannot be rebooted remotedly.
It would require to call my wife: "Darling, could you please
go down into the cellar and press that button which I marked "RESET HERE".

Doing a reboot command or typing CTRL-ALT-DEL shuts down the machine
but it then gives:

umount of /dev failed (BUSY)
Uptime: 2m2s


and then nothing. The computer sits there. Motherboard is an ASROCK
if that matters. 

Any clues? Should I post some dmesg excerpt? 

--
Chris Christoph P. U. Kukulies kuku_at_kukulies.org