yep, that's sad...
happens often to me too.
most of the time because the login has expired.
(when i notice that there is a risk, i tend to copy the text to the clipboard before posting... on the other side, most of the time, when i've lost my message, then i tend to write a shorter one, to the benefits of everybody else : - )
this having been said, if you have practical suggestions for improving the forum, we will listen...
and pray that things will change one day...