Thread:Project:Support desk/Login required twice: first login reroutes to login page/reply (3)

The cookie lines look interesting to me.

In fact, what you have labeled the "2nd login" looks like a log out. The "UserID" cookie is deleted on logout and the "LoggedOut" cookie is sent.

Does that offer any help? If not, could you send me your wiki's URL so that I can investigate futher? You can send me email if you want.