If the CD boots on another system then that leaves hardware on the system that fails, or knoppix does not have a suitable driver loaded to read the CD. Could be either.
Can you read other CD's on that system? Dirt or dust can cause problems.
If that is not the case, then post the make and model of the CD drive. You can find that out from the windoze installation. We need to know if the CD is IDE, SCSI or what ever.
BTW, the Knoppix web site has a forum and a lot of information on booting issues.
Here is a link. --> http://www.knoppix.net/forum/
Second thought, What is the system you are trying to boot this on?