---Trick to enable/diable "Task manager"---
Posted By: Abhishek Anand

* Click Start
* Click Run
* Enter gpedit.msc in the Open box and click OK
* In the Group Policy settings window
o Select User Configuration
o Select Administrative Templates
o Select System
o Select Ctrl+Alt+Delete options
o Select Remove Task Manager
o Double-click the Remove Task Manager option

since the policy is Remove Task Manager, by disabling the policy, you are enabling the Task Manager.