Do you use a seperate monitor sometimes? When you are not running the second monitor sometimes HEM will still try to maximise itself on that 2nd monitor but obviously if it is not currently connected you can't see it and so you need to move it back into view.
If this is the case then this link will help you....
http://www.howtogeek.com/howto/windo...eyboard-trick/
just alt-tab to the window, use Alt+Space, then M, then Arrow key, and then move your mouse.
^^^ that does the trick for me.