Re-enable Task Manager

1. Open regedit
2. Go to key. YOUR_USER_HASH is the key related to your own login. Usually look like S-1-1-11-111111111-1111111111-11111111-111111

[HKEY_USERS\YOUR_USER_HASH\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System]

1. Edit the name DisableTaskMgr to 0.