I just installed it. The movement control (WASD) works fine, but I can't rotate the view with the mouse. FYI, I have a Dell computer with an optical mouse I bought from Dell. Any suggestions?

This is a known problem with the 1.4 patch but easily fixed. Go to the controls menu and click the default button. This resets the key bindings and frees up the mouse.

Thanks very much - the fix you described worked great.