To minimize all open windows Microsoft provides “Hot Keys”, like Windows Logo Key + M or Windows Logo Key + D.  All Hot Keys was disabled by old GPO. To allow using Windows Logo Keys the following steps should be enabled through GPO:

1. Go to: Administrative Templates \ Windows Components \Windows Explorer
2. Change “Turn off Windows+X hotkeys” settings to Disable

Note: Client’s computer should be restarted to start using Windows Logo Keys.