How to terminate Windows task:

• Press {Ctrl} {Alt} {Del} all at the same time.
• Select Task Manager the following dialog will appear.
  
• Go to Process Tab.
• Select the task you wish to terminate.
• Click {End Process} button.

This is sometime called "Kill Running Processes".

Many programs cannot be deleted if they are currently running. Use Task Manager to stop any process that is running. (In Windows 2000 and XP, Task Manager lists all processes; in earlier versions of Windows, only visible processes will be listed.) Invoke Task Manager via Ctrl-Alt-Del. In NT/2000/XP, choose the Processes tab to list all programs. Find the exe of interest, highlight it, and end it.

Background: Windows can run many programs at the same time, but with just a single CPU, can only perform one task at a time. In your computer, Windows gives the illusion that several programs are running in parallel by switching rapidly from one to the next, giving each a time-slice of the CPU. But if any program hangs, Windows may get stuck on that task, and be unable to switch to the other running programs, causing everything to hang.

A task or process is a program (such as an exe file) that is being executed or run. When a program is started, Windows loads it into memory (RAM), adds it to an internal list of running processes, and provides the process with the memory and other resources it needs. Windows tracks what processes are using what resources, and when one of these processes is terminated, Windows can usually return its resources to the general pool, for redistribution to other processes.