Just one little question

How unactive do you have to be on your account before it signs out automatically? Sometimes I'll be in the middle of making a post and once I try to post it, it'll tell me to sign back in. Then there are other times I'll have the browser minimized for maybe a minute or two then when I bring it back up, it tells me to sign back in. I have a feeling that this has been asked but I've already searched it out and didn't find anything. Mainly I'm just curious how long you can stay unactive before you are signed out because sometimes I'll just have the browser down for a couple seconds and it'll still sign me out even if I click the REMEMBER ME box under the log in. :confused: