Photopost plays no part in the
vb whos online in any manner actually, We have our own who's online displayed on our page not vbs.
You could have it where you log out of the gallery if your cookies are not aligned properly and the user could still be logged in to the forum. I dont know enough about
vb code to assist here and given the fact Photopost does not interact with
vb's page where it has whos online I dont think this is a photopost issue. Here is your forum and it has no idea photopost is even installed on your server. There is their whos online. They are just grabbing who they say is online stored in their database. Maybe their refresh thing is not updating right. Could be a vbulletin bug.
http://www.passporterboards.com/forums/