When Snapz is invoked it will freeze your screen, cursor included. You should however see an additional white arrow cursor. If you do not see this cursor, try hitting the Escape key. You should hear a "bloop" and Snapz backs out. If this is the case for you, you most likely have a conflict with Universal Access. Open Universal Access in your System Preferences. Turn off the Zoom in the "Seeing" section and make sure that the cursor size is set to "normal" in the under the "Mouse" section. Either of these can make the cursor vanish when Snapz is invoked. Zoom is on by default and can be activated by holding down the Control key moving the mouse's scroll ball/wheel or trackpad up or down...a common accident.