Try this:
Boot from a write protected, virus scanned WIN98 Emergency Boot Diskette to the A:\ prompt. At the A:\ prompt type
the following EXACTLY, (with the exception of the <enter>).
debug <enter>
fcs: 200 400 0 <enter>
acs: 100 <enter>
mov ax, 301 <enter>
mov bx, 200 <enter>
mov cx...