I take this as rather strong indications of some kind of hardware failure/glitches. Did you check the md5sum on the download ISO, and did you burn with verification? Furthermore, are you quite sure everything works well with the file systems you run from? Occasionally, there may be small errors (reading, giving wrong initializations), but nothing as grave as you seem to experience. The safest way for me is to run from DVD, install on a flashdrive, run from that, and manually copy the whole KNOPPIX structure (including knoppix-data.img) to a harddisk partition. Booting from the flashdrive next time, Knoppix will usually find that harddisk copy first, and run that. Works safely and robustly for me. A fast (20MB/s r/w) 8GB flash drive is an almost ideal tool for normal use. You are right wrt isolinux. Directory name has changed in 6.7.0. Just leave that as it is