Tony, for Fdisk /MBR to work, it has to be a DOS boot and the system files and the Fdisk version all have to be compatible, preferably DOS 6.22 Also, only one hard drive can be present (the one with the problem).
Check your Email - I've sent a file that will create a DOS 6.22 boot floppy when it is run.
This is very easy so give it another try - you have nothing to lose.
Walt