I was having endless problems booting with the latest downloaded/burnt Knoppix 4.0 CD. After some Googling, etc, I eventually sorted out the problem.
The problem was the firmware in my Benq DW1640 CD/DVD Writer and ALL the problems (even hardware detection) were sorted out by doing a FIRMWARE UPDATE, strange as it may sound. Unfortunately I had to use WinXP to do the flashing

Just for those who may be using the same drive and also experiencing problems