Another webmail issue

While working in the webmail app, a popup appears, which looks kind of like a WMP window but isn't, allthough it IS a player.  It never successfully loads whatever it wants to show me, but it also covers parts of the page I'm working on and there is no way to close it except to reload the page.  Which of course deletes whatever you were working on, if composing.  What is it?  Why is it there (just started tonight)?  How do I get rid of it?\