Sorry if the subject line isn't at all informative; my problem is kind of hard to describe. As I'm sure you know, when you have an application with multiple windows open, you can get a layout of them on your screen by clicking the icon in the sidebar so you can select which window you would like to use. Sometimes, when I do that, it causes my computer to freeze. The keyboard still responds to commands such as CTRL-ALT-DELETE and CTRL-ALT-F2, and the mouse still moves about the screen, but everything else is frozen. How can I fix this?

Thanks.