You'd think this would be more straightforward & there would be a KB article or easy how-to on this but not that I've found. I think you need to add the missing file into dosnet.inf also so that it copies during the textmode setup - That solved my issue. Something like this : under each of these add these lines: [FloppyFiles.2] d1,fasttx2k.sys [Files] d1,fasttx2k.sys