if you can, boot to an OEM windows vista disc and go to repair my computer on the 1st or 2nd page at the bottom of the setup. Once it opens, open command ling and change directories to C: and type 'FIXBOOT' and press enter. also try 'fixmbr' and enter. then reboot and remove the CD and enter setup, F2 i believe on that laptop and make sure the hdd is set to boot first or after the disc drive.
After a reboot it should work normally. I've had the same issue numerous times and that solved it. Also i've had the same thing, but it wouldn't let me change to the C: directory. So i needed to fully recovery it by holding 'Alt' and pressing 'F10' on startup. Note this will loose all your data tho.