i could be a pop up. For some pop ups your computer will have to "connect to a server" for you to view it. And just as in a web page sometimes it doesnt connect. Since its doing all this in the background - your computer will think the pop up is the active window (window on top) - you cant click any other windows because the pop up is active and frozen, and you can close the popup cause you havent connected to the server to see it (it hasnt popped up yet) - I know it sucks, usually you can shoot to task manager and close down the explorer window that you see is the pop up. i get these all the time - but maybe its because im surfin on a 166p1