I cannot say that much about that because I only came out of my cave not that long ago...and being a caveman, am quite in the unknow on some of these finer details.
Now, what I can say, however, is that here on my PC at the house, that does happen to me from time to time. (never on the PC at school...a much better machine, at that) One thing that helps me, it seems--not that I have used it that much, actually, is to keep to pages on the browser--as one might do when waiting in CHAT--and while writing a long post, click up the other waiting page (whatever it might be) and click on something, then put it back on the tab (is that how you say that?) and go on with writing.
But I suspect that you are talking about something a little different, because I have a funny feeling that 'not being on line' and being 'logged off' are two different animals.
Please wait, and some one who is well into the Iron Age will come along and help. Sorry !! MM