I quite hope it's not your case, but the only time I dared dist-upgrade my Knoppix HD-installation, I messed it up by far too much to be able to fix it other than by a total reinstall. That's because, I suppose, Knoppix comes as a mix of stable, testing and unstable, plus a bunch of self-made packages (e.g. knx-alsa); so, having it fully rebuilt from different sources is quite likely to be as much destructive as it can.
Useless to say, but I haven't "dist-upgraded" my Knoppix since that any more...