apps(tasks) restarting even after killing them Possible Duplicate:
  Do I really need to install a task manager?
  apps automatically starting?
  How can I stop applications and services from running?  




I have some apps running in background using cpu all the time and draining my batery. I want to stop them. 

I have a latest task manager to kill the background tasks but BUT some of the tasks(apps) are restarting even after killing them, WHY ?

Is there any way to permanently kill a particular task ?
No, these tasks are services. And I think the developer starts the service START_STICKY which means, the service get every time restored if killed (normaly not through a taskmanager, only on low memory). 
I would suggest you, to remove the task manager. Android is not designed, that the tasks get killed.  If Android need memory, the system frees the ram on it own.