I have a server with software-mirrored
drives (using the Windows Disk Administrator).  Yesterday it suddenly
shutdown and would not boot back up.  It would start to load Windows and get
as far as the blue screen that shows the NT version at the top but then
after a few seconds it would reboot itself.  It would just keep looping this
way until being powered off.  No errors appear on the screen.  Safe Mode and
and
the Last Known Good do the same thing.  To get around it for now I went into
the server's BIOS and switched it to boot from Disk1 rather than Disk0.  Now
it boots up fine. (This surprised me -- I didn't have to edit the boot.ini
or anything).

I checked the mirror when it came up.  I have two partitions
mirrored on these two disks, C: and D:.  The D: partition was fine, the C:
partition was "broken", with the C: partition on Disk0 highlighted in red.
So I broke the mirror of C:, rebooted (from Disk1
again), deleted the C: partition on Disk0, rebooted again, temporarily
created a new partition with the free space on Disk0 and did a full format
on it (as a precaution), deleted that partition, then created a mirror of
the C: partition on Disk1 and the free space on Disk0.  I committed the
changes and waited for it to finish initializing.  When it said "healthy"
I rebooted and switched the BIOS back to Disk0.  I also ran diagnostics on
both disks at this point and all the tests passed successfully.
Unfortunately, the boot problem didn't go away.  The server still loops and
never boots successfully from Disk0.  I can still boot off Disk1,
and the now the mirror of C: always says Healthy, but it doesn't seem like
the mirror is doing me much good if I'll never be able to boot off Disk0.
Any help would be greatly appreciated.  Thanks!