Your account may time-out for one of two reasons. First, it has been left inactive too long and the event has updates that require to to login to access. The second reason is that you may be trying to access the event while logged into another device. You can only be logged in on one device at a time. For instance, if you are logged in on your phone, go home and login from your computer your session on the phone will be timed out and you will have to login again.