Sorry, I wasn’t meaning to be a pest, only to be helpful. I was having this problem today and thought it might help others since those were the only 2 threads I found that were related and neither one offered this solution.
I had a similar problem.
What I forgot was that I was using the wp-cache plugin and what was happening was that it was showing the cached page of the ‘enter your password’. When I cleared my cache and cookies and turned off that plugin it started working properly again.
This post offers a solution to the problem of using wp-cache with password protected posts:
http://wordpress.org/support/topic/144601
