Did Facebook just highjack my computer? [View all]

Desktop Windows 7 Firefox. I had five or six tabs open and for some reason was on Facebook which I have been avoiding lately. Everything kind of bogged down like it can does at times, but I couldn't shut any tabs I couldn't close the window I couldn't get to my email. Finally I managed to close a few tabs by clicking on the little dealey in the tray and Xing those out. Including and especially the Facebook one. So while it wasn't on a tab, the FB page was still there and I could even continue scrolling. But I couldn't shrink the window or switch tabs. I couldn't x the window out. I finally rebooted couldn't shut Firefox down had to force it. What the hell was that?