The Master Boot Record is the second most critical process, after the BIOS, that can affect the start up of your Windows computer. You PC must pass through this process successfully in order for it to boot up. As the MBR is such a critical area of a system many writers of virus programs target it. If they can successfully rewrite this record it can cause your computer to just not work at all. Boot viruses are the most prevalent types of viruses written. You need to be sure to have a good anti-virus software in order to protect your system from MBR viruses.

If you ever get stuck in the start up process you can try using the fdisk partition program. This is available for all versions of Windows and is used to re-write the MBR. In order to use this you will need your sys programs and a Fdisk. You can create your own and other useful DOS utilities as well.

If you ever need to boot from this disk in order to re-write the MBR you will have to insert the disk, usually a floppy, into the drive prior to turning on your computer. Also you need to be certain that the system BIOS will scan for any bootable disks in all the drives. When you turn on your computer and it boots from the fdisk you should see a command prompt. From there you are able to run the DOS commands that will re-write the MBR.