How to Enable Task Manager

I have found on sometimes I lose the ability to use the Windows task manager, presumably if the shop floor login doesn't have administrator rights. Here's how to get it back.

Single-line terminal command

REG add HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableTaskMgr /t REG_DWORD /d 0 /f 

If The Above Fails

Enable Registry Editor using Local Group Policy Editor 
For user using Windows XP Professional, Windows Vista Ultimate, Windows Server 2003 or 2008 with Local Group Policy Editor and has access to an administrative user account, user can change the registry editor options in the Local Group Policy Editor. 
Click on Start -> Run (or Start Search in Windows Vista). 
Enter ­GPEdit.msc­ and then press Enter. 
Navigate to the following location: 
User Configuration -> Administrative Templates -> System 
In the Settings pane, locate the Prevent access to registry editing tools option, and then double-click on it to open the settings dialog. 
Select Disabled or Not Configured. 
Click on OK button. 
Try to run ­RegEdit.exe­, and if required (still blocking yet), restart the computer.