server freezes on shutdown, problem with unmounting file system

Hi,

After a power failure my system freezes when shutting down when it is "unmounting the file system"...
It is acting as a server-gateway.
Which logs do I have to check and how can I solve this isue?
(btw I bought a UPS

)
Or is the only option a restore from CD?

In the logs i noticed this:
   /var/log/raidmonitor/current: Viewed at Wed 30 Jul 2008 02:00:12 PM CEST.
   2008-07-30 08:38:10.400874500 Event: SparesMissing, Device: /dev/md1, Member:
   2008-07-30 08:38:10.631577500 Event: SparesMissing, Device: /dev/md2, Member:
Is this a problem?

Thanks in advance.