My technical knowledge of linux is scanty indeed but to me this sounds like grub is looking for the mount point to be on the CD instead of one of the hard discs. You can check this by entering the PCLOS Control Centre and under Boot go to Set up boot system, it is the second line. If your not sure which hard disc to choose, go to Local Discs and Manage Disc Partitions. You can Check there what each of the discs is called. Important... Do not change anything in that catagory, get the name and get out.
Hope I'm not sending you on a wild goose chase...
the happy chappy