I thought Vista failing to start was a feature, something to do with enhanced security; if the OS won't start, you can't get malware!
Still on my quest to make it work. It did start first time today (amazing!) but I then loaded Office, but on the restarts, as usual, Vista crashed.
Try what I do: get it to start in safe mode (this always works for me). Once it's started, try rebooting again as normal.