Getting this reasonably frequently now:
Your submission could not be processed because a security token was missing.
please press your back button and/or refresh the page by pressing your F5 key and try again.
If this occurred unexpectedly, please inform the administrator and describe the action you performed before you received this error.
When I've used quick reply, it's just a matter of pressing submit again. But if I've gone advanced, or I'm starting a new thread, it rather delightfully loses everything I've typed and makes me want to smash things.