To Enable/Disable Task Manager

Here's How:

1. Click Start
2. Click Run
3. Type REGEDIT
4. Click OK The Registry Editor will now open
5. Browse to the following key:
   HKEY_CURRENT_USER\Software\Microsoft\Windows\
   CurrentVersion\Policies\system
6. In the right pane, look for the value: DisableTaskMgr
7. Right click DisableTaskMgr and select Delete. (When prompted with "Are you sure you want to delete this value", select Yes.
8. Now browse to the following key:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
   CurrentVersion\policies\system
9. In the right pane, look for the value: DisableTaskMgr
10. Right click DisableTaskMgr and select Delete. (When prompted with "Are you sure you want to delete this value", select Yes.
11. Close the Registry by choosing File | Exit
12. You should now be able to access Task Manager. If not, reboot into Safe Mode and repeat the steps outlined above.