There are two methods to enable Task Manager
Method 1:
• 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
Method 2:
Click Start -> Run. Type in "regedit" (no quotes) and hit Enter.
Search for HKEY_CURRENT_USER -> Software \ Microsoft \ Windows \ CurrentVersion \ Policies \ System.
Look for: DisableTaskMgr. Click on REG_DWORD. Value: 1=Enable this key (disables TaskManager); Value: 0=Disable (actually enables TaskManager)
Close RegEdit
