When I try to add a course, category, or news, I get a popup error "Error while processing the requested operation" and the course/catalog/etc. does not add.
Unfortunately I have no other information...is there a log file I can check? Since I can not add courses or categories, I am a bit limited on using this program.
Check your php.ini for the error reporting and log directives.
For example, on a Debian system, the error log file is usually located in /var/log/apache2/ folder.
Maybe your cpanel account is offering a friendly view of the log files too.