The Fdisk MBR switch is an undocumented switch that can be used with DOS fdisk to replace or repair the MBR file. This can be done if the MBR file becomes corrupted or infected. WARNING if you have a multi-boot drive you could end up loosing access to one or all of your operating systems. It would be a good idea to backup the MBR or drive before you run Fdisk /MBR. I use to have a lab where the computer and students all got infected with the NYB virus which attaches itself to the MBR files and then infects any drive that reads or writes files from the hard drive. To correct the problem and get rid of the virus we would boot the computers from a clean DOS floppy or CD and run fdisk /mbr and this would correct the problem. Once the student floppies or flash drives got infected the virus would migrate rapidly throughout the lab. I wasn’t until we put on a good anti-virus program that we were able to clean and rid ourselves of the problem. The fdisk mbr switch has helped in the past but good anti-virus software is a better long term fix.
FIXMBR
The FIXMBR website has some additional articles you might find useful.
