The reason is most software is designed to be installed on hard drives, and CD's are read only. When the computer tries to write to the CD drive, it will indicate an error and close. RCTC supports both the Windows and Macintosh environments. Make sure you check out the correct version from the library or your CD will not function. This should be indicated in the syllabus from the instructor, but in general there are a few preferred methods.
Some classes use dropboxes within class sites.
These stay within the course setting, and can be returned to students. In extreme cases, files are saved to CD or disk and sent to the instructor, or brought to campus if possible. It is also possible to request a hardcopy print of work, but arrangements should be made prior to due date. This is often due to high security settings within corporate environments. Sometimes a security administrator may set the firewall to prevent applications such as KeyServer from opertaing within their network, leading to error messages.