I am now also having these exact problems. I can access the rest of the site just fine, 'Albums', 'MoT Chat', 'Forums', not a problem. But the moment I try to open the 'Posts' page, I get the blunt "access denied" message.
Now I'm not expert in computer programming or related subjects but I noticed after removing all my cookies, I I reentered my log in information to the site and I could view the 'Posts' but it is strictly a one time event. After refreshing the page or moving to another area of the site, trying to return to 'Posts' results in the "access denied" message again.
I don't know if you already have a fix for this but I hope this additional information helps solve the mystery if it's not already solved.