Mouseover not working with all users?

[wideopen]

Can someone help me out? When a user mouses over a thread title, it usually gives the first few lines of the thread. I have some users saying it isn't working for them? It doesn't seem to matter which browser they are using be it IE, Firefox or Chrome?

Any Ideas where to start?

Java Problem?

I just don't understand why it's working for most users but not all?