Keeping finding myself Logged Out..

On my home computer I've got EF set to remember me but at work not so after clicking on a few posts I keep finding myself for some unexplainded reason logged out. Is this a normal occurance when I haven't set EF to remember my log in details..? I would think EF should keep me logged in as long as I don't close the current browser window.

[Swisskid10]

It seems that after a certain period of not doing anything, it logs out