WOW!!! "knoppix nodma" works! Thanks a lot.

But what is this DMA thing anyway? And why was it causing problems? Are there any performance issues I might have to face?

I am already facing a problem, don't know why. My USB drive does not work under Knoppix. When I plug it in, I can see its icon on the desktop, but clicking on it gives me the message "Could not mount device. The reported error was: mount: I could not determine the filesystem type, and none was specified." Can somebody help?