This happened over at wotc too.
I've got a window, and a second window.
I start to write a post
click over to the 2nd window
click back to the 1st window
Then I get this:
The following error or errors occurred while posting this message:
Your session timed out while posting. Please try to re-submit your message.
Try it a bunch of different ways, but it keeps happening.
Never had this problem before, using to windows for a post.
I know it's something I'm doing, but I don't know (at all) what it is.
Just had a Firefox update, so it might be connected.