I/O error from bootable CD

Greetings. I downloaded 5.1.1 and burned a CD. When I put it into my laptop and boot I get an error partway into the sequence. Here is what I see (I replaced some text with ...):

Running Linux Kernel 2.6.19
Total Memory...
Scanning...
Enabling DMA acceleration for: hda [IBM-DJSA-220]
Enabling DMA acceleration for: hdc [HITACHI DVD-ROM GD-S200]
Accessing KNOPPIX CD at /dev/hdc... insmod: can't read '/cdrom/modules/cloop.ko': I/O Error
Can't find KNOPPIX file system, sorry.
...

I'm dropped into a small command line interpreter. I know the drive works, because I can get to Windows with it normally and I can boot with it using some other boot disk.

Any ideas where to go from here?

Please see answer #1.

I'm on it. Thanks for the pointer.