Accessing the resource ‘\\servername’ has been disallowed

On a remote desktop server I got the message: Accessing the resource ‘\\servername’ has been disallowed when trying to access \\servername from file explorer.

The GPO setting that caused this was:
User Configuration/Administrative Templates/Start Menu and Taskbar/Remove Run menu from Start Menu.

When i disabled this setting the users could access servers from file explorer.

GPO to Hide Control Panel Items

Path in Group Policy Management Console: User Configuration/Policies/Administrative Templates/Control Panel/Hide specified Control Panel items.

Values:
Microsoft.AdministrativeTools
Microsoft.ActionCenter
Microsoft.AutoPlay
Microsoft.DefaultPrograms
Microsoft.DeviceManager
Microsoft.iSCSIInitiator
Microsoft.NetworkAndSharingCenter
Microsoft.PhoneAndModem
Microsoft.PowerOptions
Microsoft.ProgramsAndFeatures
Microsoft.RemoteAppAndDesktopConnections
Microsoft.System
Microsoft.TextToSpeech
Microsoft.Troubleshooting
Microsoft.UserAccounts
Microsoft.WindowsFirewall
Microsoft.WindowsUpdate
Flash Player
Java
Install Application On Remote Desktop Server

More values can be found here.

QuickTime and Windows 2008 R2/IE8

If you running a Remote Desktop Server under Windows 2008 R2 and have installed Apple QuickTime, remote dekstop users might get this meassage when they try to view for example trailers at apple.com:
Download QuickTime to view this video.

To solve this you need to either add the website to sites under trusted sites in internet options or enable “Script ActiveX controls marked safe for scripting” for the internet zone in internet options.