This seems to be a hit or miss problem for me when logged in, but I've noticed that when I'm viewing a thread and I click on the MR logo on the upper left to go back to the main page or click the bookmark on my toolbar (to the same page) it logs me out. It seems to happen every 3-4 times of logging in. I'm not sure if this is the forum or my own version of Firefox causing this... any input?