I am using Mozilla Firefox 7.0.1 on a Windows 7 computer (home basic). I usually keep the browser window opened for a long periods of time, like three to four weeks, and I have many tabs opened in the window, like 300 to 900. Recently all of the sudden the Firefox window became "always top" window. I can minimize it, but when it is maximized, no other window can be displayed in front of it, only behind it. This is very inconvenient for me. Is there any fix that I can apply without restarting the Firefox window?

Thank you.