I have tried Knoppix 5.3.1 on four different computers and get the same results. As the Kdesktop is opening, I see "Kdesktop crashed and has caused signal 6 (SIGABRT). I then close the error and everything else seems to work but the system disk has not been mounted. There is no HDA1 or SDA1 on the desktop. It does mount a USB drive ok.
I also have Knoppix 5.1.1 and it boots up and mounts the system disk just fine on all four of the computers. All four systems are running various versions of Windows just fine.