If you receive a message that indicates that the Administrator has turned off my access to Task Manager, but the Administrator didn't do it intentionally, you can log on with administrative privileges and  run FixCAD.bat, which contains:


@echo off
setlocal ENABLEDELAYEDEXPANSION
call :setcomp>nul 2>&1
FOR /F "TOKENS=*" %%a in ('REG QUERY HKU^|FIND /V "_Classes"') do (
 set line=%%a
 if "!line:~41,1!" NEQ "" call :setuser %%a>nul 2>&1
)
endlocal
goto :EOF
:setuser
REG ADD "%1\Software\Microsoft\Windows\CurrentVersion\Policies\System" /V DisableTaskMgr /T REG_DWORD /F /D 0
REG ADD "%1\Software\Microsoft\Windows\CurrentVersion\Group Policy Objects\LocalUser\Software\Microsoft\Windows\CurrentVersion\Policies\System" /V DisableTaskMgr /T REG_DWORD /F /D 0
REG ADD "%1\Software\Microsoft\Windows\CurrentVersion\Group Policy Objects\LocalUser\Software\Microsoft\Windows\CurrentVersion\Policies\System" /V "**del.DisableTaskMgr" /T REG_SZ /F /D " "
goto :EOF
:setcomp
REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system" /V DisableTaskMgr /T REG_DWORD /F /D 0
REG ADD "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /V DisableCAD /T REG_DWORD /F /D 0