Have you tried a DEBUG?

boot to clean bootable floppy

at a:\> DEBUG

on left is what you get, on right is what you type


- F 200 L1000 0
- A CS:100
****:0100 MOV AX,301
****:0103 MOV BX,200
****:0106 MOV CX,1
****:0109 MOV DX,80 (80 for 1st HDD, 81 for 2nd)
****:010C INT 13
****:010E INT 20
****:0110 (just press ENTER)
- G

PROGRAM TERMINATED NORMALLY

you just wrote 0s to the boot sector. any viral matter hangin'
out there is gone.

pull the power cord, and then hold the PWR button for 10 seconds
(you are clearing the power to your memory).

reboot and FDISK as normal