Windows 2000 Native UPS uncommanded Shutdown

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Help! I have a dual OS (XP Pro and Win 2000) system - RAID 1+0, ea OS
on a separate partition. I am using an APC batt UPS and have APC's
PowerChute Personal ed software loaded in both OS's. Unfortunately in
my ignorance, I also enabled the native UPS power optiosn within ea OS
also. (XP is now disabled again, but read on for 2000)
Up until the first battery switching events (undervoltage events), I
had no problems booting into either OS, but since those events which
occured while XP Pro was 'up', I cannot successfully boot into Win 2000
- the native UPS begins an immediate shutdown as soon as Windows 2000
starts. I've tried literally racing it to get to the Admin Options/UPS
service and disable that before the shutdown completes, but so far
haven't won!!
I've deleted the APC files within 2000's file set, and even tried
restoring older drive images (from before the battery switching events
even), but the same problem persists. Short of reformatting that C
drive (XP is on the D drive) and then trying an image restore, I don't
know what else to do at this point.
Hoping one of you MS MVP's might have an insight before I take this
drastic action! If I do reformat the C drive, will that cause XP, on
the D drive, problems? The AUTOEXEC and CONFIG files *all* reside on C
(ie. nothing on the D drive)

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