Heidi,
Hmm. A character encoding issue in the original media, perhaps? Others may want to chime in.
Could you run the following command in a terminal and send me the output? You'll need to replace /home/bcadmin/Desktop/testcd.iso with whatever the path to your filename is.
I've included sample output so you can see what it should look like. I'm specifically interested in the Data preparer id and notes about Joliet and Rock Ridge extensions, as a start.
bcadmin@ubuntu:~/Desktop$ isoinfo -d -i /home/bcadmin/Desktop/testcd.iso
CD-ROM is in ISO 9660 format
System id: CD-RTOS CD-BRIDGE
Volume id: SEP_06_2007
Volume set id:
Publisher id:
Data preparer id: IMAPI ISO-9660 Formatter Copyright (C) 2001 Microsoft & Roxio
Application id:
Copyright File id:
Abstract File id:
Bibliographic File id:
Volume set size is: 1
Volume set sequence number is: 0
Logical block size is: 2048
Volume size is: 113758
isoinfo: Warning: Joliet escape sequence uses illegal space at offset 3
Joliet with UCS level 3 found
NO Rock Ridge present
bcadmin@ubuntu:~/Desktop$