> Task Manager has been disabled by your administrator .

“Task Manager has been disabled by your administrator”

Here is solution from the Microsoft article about enabling the task manager:

Enabling Task Manager from Group Policy Editor

• Go to “Start” -> “Run” -> Write “Gpedit.msc” and press on “Enter” button.
• Navigate to “User Configuration” -> “Administrative Templates” -> “System” -> “Ctrl+Alt+Del Options”
• In the right side of the screen verity that “Remove Task Manager”" option set to “Disable” or “Not Configured”.
• Close “Gpedit.msc” MMC.
• Go to “Start” -> “Run” -> Write “gpupdate /force” and press on “Enter” button.

Enabling Task Manager from Registry Editor

• Go to “Start” -> “Run” -> Write “regedit” and press on “Enter” button.

Warning: Modifying your registry can cause serious problems that may require you to reinstall your operating system.
Always backup your files before doing this registry hack.

• Navigate to the following registry keys and verity that following settings set to default:

Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System]
“DisableTaskMgr”=dword:00000000
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Group Policy Objects\LocalUser\Software\Microsoft\Windows\CurrentVersion\Policies\System]
“DisableTaskMgr”=dword:00000000

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system\]
“DisableTaskMgr”=dword:00000000
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]
“DisableCAD”=dword:00000000

• Reboot the computer.