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.