Problems with Boot

So I go to put knoppix on an old (2001) gateway computer with no current operating system on it. I get an error message that says
Unfortunately, the device system:/media/hdc (/dev/hdc) named 'KNOPPIX' and currently mounted at /cdrom could not be unmounted. The following error was returned by umount command:
umount: /cdrom is not the fstab (and you are not root)

How do I fix this?

I also get a KDesktop - The KDE Crash Handler message. It says

The application KDesktop (kdesktop) crashed and caused the signal 6 (SIGABRT).

Sorry for the questions, its late, I'm tired and I just want this thing to work.

What are you doing to the system when this message appears?
Are you clicking on the icon and trying to unmount it?

Which version of knoppix are you using?

I'm just sitting there waiting for everything to load up. Then I start getting the error messages. I got 4 of the same ones.

5.1.1 cd

Ok, you say you're reaching the kde desktop (well almost if it crashes).
Think you've probably got either a combination of a CD/DVD rom with dirty lens, not reading the CD, or perhaps a bad media.
If you've burnt the iso image from windows try writing at a slower speed, x4 or x2.

The knoppix CD's are heavily compressed (around 2G to fit on a 700M image) which is why they are slower to load. Windows
is not the best system at burning CD's and this could be your problem, or maybe the system doesnt like the brand of CD-R youre
using. Hope that helps.

thanks, I burnt it using alcohol 120% and I'll burn another copy at the slower speed and get back to you.

Thanks for your help.

Now its saying the device was successfully unmounted, but the tray could not be opened.