It happens many times when you run a program which consumes a lot of resources in terms of Memory and CPU, but when you try to do some other operation on windows with this program running, it gets hanged and goes to not responding state in windows.

In not responding state the program windows does not respond and gets faded in general, at this point of time you are left with no other option to end the program, so you will either need to kill the process via windows task manager. But killing or stopping a process via task manger can be quite cumbersome and complex for a normal user who is not used to using task manager.

In such a situation you can use a free program called Process Manager which embed the option of killing the process or changing its priority.

Kill Process or Change Priority When A Program Goes Not Responding | TroubleFixers – All about fixing computer troubles.