MyBB Community Forums

Hi, I have a problem because when you want to log on to the forum it shows the login, and writes that logged but not all the time tells logged log in and nothing gives the ACP the same thing the first time the logs but to some it will come tab makes login again and how it logs do not want to log in. Others have the same problem on my forum. Please help! Sory for the mistakes but I do not know English well.