Having had a few "Page cannot be displayed" incidents when posting to the forum, I've lost my carefully typed and formatted replies more than once when I Preview or Post. And had to start all over again.
So now, I do a select all (PC [Ctrl]+[A]) and copy to clipboard (PC [Ctrl]+[C]) before I Preview or Post. That way, if I do lose context in my browser, I can just paste (PC [Ctrl]+[V]) it back in and nothing is lost.
Doesn't happen often, but it saves a lot of anguish and gnashing of teeth when it does. Hope this helps anyone else who's had that problem.