I did an apt-get upgrade after a new installation of Knoppix 3.6 to my hard drive, and ended up with many KDE issues like kmail not starting and editors not working from konqueror to name just two. I would strongly recommend you do not do this unless you really know what you are doing (obviously I do not). I had to fix the problem by a complete new install of Knoppix.
I hope this note will save others some grief.