Open the registry and find the key below. 

Modify the value of 'AutoEndTasks' to equal '1' to automatically end tasks or '0' to prompt for action. 

The default time-out before ending the task is defined by the value of 'WaitToKillAppTimeout' located in the same key, this value is in milliseconds (default = 20000 i.e. 20 seconds). You can therefore additionally change this value to speed the process up. 

Note: This change will affect all users but value can also be changed on a user-by-user basis by modifying [HKEY_CURRENT_USER\Control Panel\Desktop] and the same values. 

Key:[HKEY_USERS\.DEFAULT\Control Panel\Desktop]
Value Name: AutoEndTasks
Data Type: REG_SZ
Data:(0 = disabled, 1 = enabled)

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