Can't reboot after power failure (RAID problem?)

[davidg@alcor.concordia.ca]

My system went down because of a power failure, and now it won't start.  I
use RAID 1, and I don't know if that's related to the problem.  The screen
shows the following.

Loading, please wait...
Gave up waiting for rood device.  Common problems:
- Boot args (cat /proc/cmdline)
  - Check rootdelay- (did the system wait long enough?)
  - Check root- (did the system wait for the right device?
- Missing modules (cat /proc/modules; ls /dev)
ALERT! /dev/disk/by-uuid/47173345-34e3-4ab3-98b5-f39e80424191 does not exist.
Dropping to a shell!

I don't know if that uuid is an MD device, but it seem likely.  Grub is
installed on each disk, and I previously tested the RAID 1 arrays by
unplugging each disk one at a time and was able to boot to either.

Ideas?

David