How to Pause,Halt,Stop a Program

Hello Fellas,

I have a question to ask about how to halt,pause or stop a program from running using microsoft visual basic 2010?

Sorry but i dont have a code to show ya....
Example i want to halt, pause of stop firefox.exe from opening or being executed using Vb.net 2010?

If you some ideas ideas. Please respond to this post..

Thank You!