MyBB Community Forums

Some off the users at my forum cant login. Or when they type in right username and password it says they have logged in and when it goes back to the forum it says you are logged out. Some users get in but others dont. What is wrong?

I just set up a brand new install on my test server and I have the same problem. I just found this and it worked.

http://community.mybboard.net/thread-42123.html