I hope I can jump on this because I was having the same problem.
Originally my user database was tied to phpbb and I changed it to vBulletin.
It took some editing using phpMyAdmin to get everything working.
it seemed to be a Catch-22 trying to change the setting in the admin section.
Anyway. . .
I edited the cookies settings as above.
My problem is that I can't log out of PP unless I log out of vB first.
There is always a catch 22 on this. You need to change the configuration file as well as the options in the database which are two separate actions which means after changing one you cant do the other without editing a file or the database
I dont beleive anyone here has looked into the possibility of placing all the config file settings and forum options onto one section as its never a good thing to switch integrations midstream for obvious reasons of Photo Ownership since userids change. All you end up doing is messing up your installation.
That is what I thought. Everytime I would change one place I was nopt able to change somewhere else. Then I'd restore back to normal and try again. After taking some deep breathes I edited one of my config files manually and made my other edits through phpMyAdmin. Plus compared my other PP install that uses vB.
But I still can not log out from PP unless I log out of vB first.
Is that a cookie issue? I cleared the cache. my cookie is bb as instructed above.