I'm getting this too - each time I try to post or reply. Then if I try to logout, it gives me an error. I have to manually enter '...action=login' to get to the login page and re-login. BTW, I've tried both the minutes timeout (60) and always-logged on. It happens at home and at work.
It just happened when I hit 'Post' for this reply:
Your session timed out while posting. Please try to re-submit your message
And when I tried to log out:
An Error Has Occurred!
Session verification failed. Please try logging out and back in again, and then try again.
So I had to manually enter '...action=login' and start over.
Matt