Im just doing a follow up on this...
I remember fixing this issue but dont remember what I did back then but I just tested my site to see if i could duplicate the problem again and it no longer does it, I beleive what was changed to fix this was filling in the domain name within the custom setting box under cookie domain within Vbulletin's admin control panel. I added .domainname.com into the custom setting box.
Im pretty sure this is what I did to fix this.
Anyway I just wanted to do a followup on this in case someone is experiencing this problem.