Cannot prevent user registration
 

I have read several threads on here and bookmarked something (which i am currently trying to locate!) to stop spammers registering using something from the vbadvanced site i seem to recall* but in the meantime* cannot turn of the user registration processs from with general options.
I have disabled VB advanced (within the panel); i read this won't happen (with vb on it's own) although get an error when attempting to view the site of;

Fatal error: Call to undefined function: print_portal_output() in /home/name_of_db/public_html/forum/index.php on line 46

until i turn it back on* in which case it's fine. I know there is no support on here for vbadvanced* but would like to know what may be preventing me from people registering until i get the other method from stopping people registering when they are spammers!

Thanks for looking!