Okay, this has been replicated by me, but my computer is in the process of trying to die, so I'm not sure if it's the boards or my computer.
I was on the Coffee Break folder, and I went into a thread. When I used my browser's back button to go back to the Coffee Break thread (easier than trying to reload it fresh for IE right now) it loads a cached version of the page from this morning. I know it's a cached version from this morning, because I remember being excited about a certain few threads that had new posts, and the first time this weird redirect happened I was confused that all the exact same threads had new posts, but I couldn't find the posts in the thread.
When I do click the link across the top to reload the Coffee Break folder, it works fine. But it's the only folder that loads a cache when I use the back button, everything else just goes to the last version of the page that's loaded (so everything I'd read before clicking on that individual thread is still marked read, things are in the same place I left them.
Is anyone else having this problem?