Computer freezes after resizing window

When Minecraft launches it starts of in a small window. Occasionally (Twice now) when I try to expand the window the Window expands but not the actual game, It stays the same size stuck in the corner. When I go to shrink it back to it's original size my computer freezes and I have to shut it down and restart it. This gets really irritating
Notes
-Background audio continues to play from other applications but not Minecraft
-Mouse reacts to movements