|Some of these programs may not be completely closing when you close them. If Task Manager does not help enough, download Process Explorer from Microsoft because it will tell you more about what is running on your system.|
"it is difficult for me to format my system totally, as i am keeping lot of important files in it." Back up, back up, back up. The more important the information, the more important the back up is. Get an external hard drive or a second internal hard drive for your back ups ($40.00 - $60.00 typically)
You have to be a little bit crazy to keep you from going insane.