Many possibilities, amongst which:

- if you've got an old DOS boot-diskette, run fdisk/mbr from it
- if you've got a genuine NT/2K/XP MS cd (not a crippled restore only OEM one), boot to the recovery console, then issue "fixmbr"
- strip down your /etc/lilo.conf to only contain the windows entry, set the timeout to zero, install to MBR ("boot=/dev/hda"). then run "lilo -v".

Also, make sure your windows primary partition (probably /dev/hda1) is the only one marked active/bootable.

Oh, and thanks for flying knoppix airways ;-}