I had a similar problem with my LTD-166s : try Flashfix to disable the checking for the right DVD by the flasher. Just be very carefull that you don't select the wrong drive to flash, as the flasher doesn't check this anymore.
I believe it's on the "LiteON utilities" page.
Look for the file "Flashfix1119.zip". Also , don't forget to put UPX.EXE in the sane directory !