windows trying to reinstall on reboot ? ? ?

[PhilliePhan]

One thing that may be best to do first, is to return hard drive as a slave on the other Pc and backup any needed data etc externally..Cd..Flash drive etc.

I agree - That would definitely be my first step before trying anything else!

Safe mode via msconfig is becoming increasingly dangerous these days due to some malware wiping the safeboot registry key:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Contro l\SafeBoot

And msconfig, as you noted, changes boot.ini - the only way I know to fix this is through the recovery console. Slaving the drive as you did was a great idea. I can't believe that never crossed my mind!

That said, I am not sure how to address the current issue. . . . However, in addition to what The Saint has posted, you might have a look at this link as your penultimate (next to last ) resort:

XP's No-Reformat, Nondestructive Total-Rebuild Option

Best Luck
PP