A+: Diagnostic Utilities and Tools for Boot Failure

Boot sector viruses and magnetic errors can corrupt the master boot record (MBR), which is used by the BIOS’s bootstrap program to locate a bootable drive. A damaged MBR will prevent your system from starting from a bootable hard disk. To repair a damaged or corrupted MBR, you can use one of the following options:
• Windows Vista users can use the Command Prompt within WinRE (System Recovery Options) and type the command bootrec /fixmbr to repair the MBR. To repair the damaged Boot Manager program, the command would be bootrec /fixboot. For more information on this fix and other related fixes, see the following link: http://support.microsoft.com/kb/927392.
• Windows XP/2000 users can use the Recovery Console command Fixmbr on an NTFS-based drive. If the drive is FAT based, first use Fixboot, followed by Fixmbr. To rewrite the boot sector on a FAT-based drive, type Fixboot and press Enter. To repair the master boot record with an NTFS-based drive, type Fixmbr and press Enter. (If you boot from a different drive letter than the default Windows drive or a different hard disk than normal, you can specify the hard disk drive letter or drive number with these commands.)
Because damaged MBRs can be caused by a computer virus, you should test systems with an up-to-date antivirus program before using either of these commands. If a boot-sector virus is located by an antivirus program, the program’s own disk-repair options should be used first. Don’t forget that many BIOS programs come with the option to scan the boot sector for viruses. If you have this functionality in your motherboard’s BIOS, consider using it! If this is unsuccessful, you can use the appropriate repair tool to attempt to fix the MBR.


If you see a message at startup referring to EZ-BIOS, Dynamic Drive Overlay, or a similar message, it indicates the drive has been prepared using a third-party disk utility, such as old versions of DiscWizard, Disk Manager, MaxBlast, Data Lifeguard Tools, or other vendor-supplied hard disk setup programs. If a system has an outdated BIOS that cannot manage the full capacity of the drive, these programs will install a nonstandard MBR and drivers to manage the drive’s full capacity. If systems running third-party hard disk management software can’t boot, use the repair program provided by the software vendor, not Windows’ own MBR repair programs.