Thanks for all your help guys. To make a long story short, after countless trials and tribulations, I've fixed the problem. I can't tell you what the solution exactly was though--- I was so desperate, I was changing many things at once, but having the member directory in the same path as the cgi's, as well as zapping vars_config and starting fresh seems to have done it.
BUT
I now have a new error. This error is more minor, since the board still works with it.
All the URL's are appendede with a =nfx when a user is logged in. According to CC:
https://www.ubbdev.com/forums/ubbthreads.php/ubb/showflat/Number/181552/page/110"nfx == No File_eXists, meaning that the currently logged in user's profile is missing."
I assume CC means missing from the cache?
The board works fine, its just that the cache hit is reduced by almost two thirds.