Sometimes some windows get hidden

Hello, this program is great, only 1 tiny bug: sometimes it makes windows moved to the left, beyond the left screen border, so they are invisible. Also, they are resized to be very small, as if I did it manually, but I did not. I have no problem to get the windows back to the visible screen by Alt-space then right arrow then move mouse, yet it's a bit irritating. Can't reproduce, it happens random. Note that I have my taskbar on the left side (Windows 7).