The FIXMBR recovery console command can be used to fix the MBR file. The MBR file is
FIXMBR
the first sector (512 bytes) on the hard drive and therefore can be subject to virus infections and other problems. This file contains hard drive partition information, boot record pointer information, and information for boot strapping the operating system. The Fdisk DOS utility will do the same thing in the DOS that FIXMBR does in Windows Recovery Console.
The Windows Recovery Console can be started by booting the computer using the Windows install CD to run FIXMBR. If your computer didn’t come with a Windows install CD. You can make one using nLite and the i386 folder on your computer. nLite is a great free utility that can be used for creating a custom Windows install CD that is fully automated and setup to include all drivers, service packs, security patches, and other important files you might need. You can also use nLite remove keyboards, languages, and other files to lighten the size of the Windows install disk which will provide a faster installation.
The Computer Technology Training website has some additional information you might find helpful.