Been there done that... Sadly!
One habbit I adopted long ago was to copy and past my post to Word. Not just for grammer and spell checking but as a holder should something happen.
It seems the few times I wouldnt follow that method is just the very times it would happen.
However what can be done to fix it? I'll look and see if it's possible to extend the session id time. Which if i had to guess is key to your problem.