A system critical file was corrupted during the power interruption.
You may be successful in attempting to repair the OS, but you may end up having to re-install the OS to fix the problem.
In either case, you will need a functioning Vista disk.
Often the manufacturer will have a recovery partition on the disk. Go into the BIOS and select this partition to boot up to. This will give you the option of re-installing the factory image. But you will loose any files on your system unless you can back them up while in safe mode.