Preliminary guess; your connection has been reset or the computer you are on does not retain the necessary information to keep the login current with WP. Then after a length of time, when you go to submit the message, the site does not recognize you as a valid, logged-in member and will therefore not accept your post. I would not get too concerned with this offhand.
M.
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My thanks to all the wonderful members here; I will miss the opportunity to continue to learn and work with you.
For those who seek an alternative, it is coming.
So long, and thanks for all the fish!