ElkArte Community Modern, Free, Powerful
Community building forum software

It isn't the cache. It must be the IE9 at my office as it's the only browser I tested which has this problem. This IE also has a problem with drag and drop when arranging smilies or boards (sometimes it doesn't work and I must refresh the site).

If it always only your IE9 at work, it may be some strange config... dunno.
If you or anyone else is able to reproduce it, feel free to post new info!