How to fix "Task Manager disabled" by Administrator

If you're not part of domain environment and one day find that you're unable to access the Windows Task manager due to the error message below, there's a good chance you've been infected with a virus.

You can fix this using the following method:
-Click Start -> Run

- Paste the following command into the Run dialog box:
REG add HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableTaskMgr /t REG_DWORD /d 0 /f

-Click Ok