Interesting...

You're booting from CD and can't get the hard drive mounted read/write. You've tried right-clicking the icon and removing the x from the read only bubble I assume? Is that the "actions submenu"? I've had some trouble with Knoppix in that sometimes I have had to open a Root Shell and unmount the drive and remount it from the command line. Perhaps this is what you must do:

Code:
$ umount /dev/hda1

$ mount -w /dev/hda1 /mnt/hda1
Okay, the -w will mount the partition as read/write. Note that the above example uses my first partition hda1. I don't know how your drive is partitioned, but you may need to adjust the 'hda1' depending on your setup.

You should try the above code and see if that works.

Hope this helps.

James