I don't follow here
I created a username on your site and logged in on your homepage
I then went into classifieds and was logged in fine.
I hit the logout button and was logged out fine.
What domains are you running your nuke on? Nuke doesnt have cookie settings that I can tell. Everything is hard coded. Your cookie path is /php/ and as such your cookie path in classifieds is set to /php/. There is no way that I see to set your cookie domain other than blank in nuke.
If I go here http://villanofun.com/php
and login and then go here http://villanofun.com/php/classified
I am indeed logged in and if I hit logout I am indeed logged out in all products.
I would suspect your trying to login to your nuke site from http://www.villanofun.com/php
in which case your not going to be logged into classifieds
You can set your forum in nuke and classifieds to use .villanofun.com as the cookie domain so www.villanofun.com
and villanofun.com both work but the real problem exists in Nuke. Where can you set the cookie domain to .villanofun.com in NUKE so your user cookie will work on either domain
I hope you follow what I am saying as most products your able to set COOKIE SETTINGS