Have seen this several times. Win 7, 64bit, ST2 build 2111. I have several files open in one window. Grab the tab of one file and drag to the desktop. Usually, you get a new window with just one file in it. (I *love* this feature, btw!). Sometimes, however, the window seems to never get created or something. The OS thinks the window exists, because it appears as an icon/text thing in the task bar at the bottom of the screen. But clicking the task bar icon does *not* bring up the new window. It's just dead and can't be accessed in any way, apparently. Hot exit from ST2 and a re-start fixes things.