Some applications aren't ended completely when your mobile phone returns to the home screen. They keep running in the background unless you end them from the list of active applications.
View list active applications
End active applications
Tap and hold the Menu key until the list of active applications is displayed.
Return to the home screen
Tap the required application.
Tap the Menu key.
Tap the Return key to return to the home screen.
*Please refer to the BlackBerry website for more information or further support.*