I have been following CGcookies blender intro course and I’m currently on their texture lecture. At one part of the video the instructor uses circle select in UV map view, then presses “S” to scale the faces, when I do it my blender freezes. Well action the only part that doesn’t freeze is the UV view where I can still circle select more vertices. Everything else just becomes a wallpaper, 3d view no longer turns, buttons no longer clicks, none of the drop menu works, short cuts doesn’t work. When I bring out my process manager all I see is blender is still functional instead of application not responding. I have recreated this problem many times already because I have the blend file. Is this a known bug will a fresh reinstall work?
Hit the Escape key to go out of Circle Select mode and all will be well. 
That’s just the way Circle Select works. Unlike Box Select that, once you’ve outlined the box, automatically drops out of Box Select mode. With Circle Select, you always have to Esc out of it.
Right-click works too.
-LP