Thanks Paulus Magnus, I've fixed my typo (incredible how those always manage to sneak in!) and the directory checking should work now (for some reason I had placed it outside of the routine where the IPs are logged).
Eaglecrew: The changes are in the following files:
ubb_registration.cgi
ubb_new_reply.cgi
ubb_new_topic.cgi
cp_users.cgi
ubb_lib_idle.cgi (just overwrite your old one)
And all of the templates listed in the text file (you can safely overwrite cp_user_ips.pl with the new one

).
ZIP has been updated with the fixes mentioned above.