This isn't a real problem, I think. It's only a minor inconvenience. Every time I spend some time on Firefox (version 2.0.0.3), a small title bar without a window pops up on the lower-left of my screen:

The title bar cannot be right-clicked, can be moved, and closes whenever I press CTRL. So, as you gather, I can't see from the Task Manager which program it belongs to.

What is it, and how do I stop it from appearing? I've tried browsing several websites, and I think it comes up when I visit J2O or JCF, but I'm not sure.