Windows Task Manager is a task manager application included with the Microsoft Windows 7 that provides detailed information about computer performance and running applications, memory information, processes and CPU usage, system services, network activity and statistics, etc. If you have an application that just doesn't respond or hangs, you can close it using Task Manager.
Right click on the taskbar
choose "Start Task Manager"
Select your application
Right click on it then select "Go To Process"
Right click on highlighted process, and then select "End Process"
If an open program is associated with this process, it will close and you will lose any unsaved data. If you end a system process, it might result in an unstable system. Are you sure want to continue? Click "End Process"