When I used to move my mouse across a thread title, or other things on a screen on all websites, a little box would open with a brief explanation of what you are touching, it hasn't done it for me forever and I want it back, how?
Might be an issue with your browser, IE I assume?
If so download Google Chrome or Mozilla Firefox. Or the new IE if you really want to stay with microsoft products.
...However the forums being upgraded to 4.0 when ever Li gets around to getting it done. And, I'm sure the changes we see will be greater then the issue you're having.
(There is a few -many- conflicting CSS errors which are probably why the site has broke for you.)
If you REALLY REALLY REALLY dont want to change your browser because of bookmarks and stuff, try clearing your browser cache.