Install ubcd 5.0beta12 to your usb flash drive, after extracting contents of ubcd50b12.iso find ubcd50b12\ubcd\tools\win32\ubcd2usb\ubcd2usb.cmd and run it...will give you further instructions to format and copy of the correct files for you. After it is finished boot from the usb flash drive and run the main item called Parted Magic. It will allow you to access all of your files and backup important documents. After that is finished, and being still in parted magic you can format/partition the HD.
OR, you could trying doing a vista repair...if you still have vista dvd, you can boot from it and select repair my copy of windows. I dont know the options off the top of my head, but one of them should help you repair the current vista build.
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~Just StopSpazzing~
Visit the UBCD Wiki:
http://wiki.ultimatebootcd.comPlease check your
UBCD ISO
MD5 Hash Sum; May prevent issues later on by not having an exact copy.
Currently Working on
Common Issues and Repair Tips on the Wiki.