Use the Vista installation DVD repair prompt. Boot the system to the Vista installation DVD. To do this in BIOS set the first boot device to DVD and save and exit.
1. Put the Windows Vista installation disc in the disc drive, and then start the computer.
2. Press a key when you are prompted.
3. Select a language, a time, a currency, and a keyboard or another input method, and then click Next.
4. Click Repair your computer.
5. Click the operating system that you want to repair, and then click Next.
6. In the System Recovery Options dialog box, click Startup Repair.
7. Restart the computer.