I've got this small gray box on the top-left corner that stays above all windows. Right-clicking etc on it does nothing.

You can see it on top of the recycle bin icon in the pic above. What is that? I checked the Users tab on task manager and I was the only user running, I tried closing a bunch of running apps in system tray, etc.
stays above all windows. I am not a Windows user, so I might be wrong, but I think such an indicator would not stay above all windows. – VL-80 Jan 19 '15 at 01:56