Prevents users from using My Computer to gain access to the content of selected drives.If you enable this setting users can browse the directory structure of the selected drives in My Computer or File Explorer but they cannot open folders and access the contents. Also they cannot use the Run dialog box or the Map Network Drive dialog box to view the directories on these drives.To use this setting select a drive or combination of drives from the drop-down list. To allow access to all drive directories disable this setting or select the "Do not restrict drives" option from the drop-down list.Note: The icons representing the specified drives still appear in My Computer but if users double-click the icons a message appears explaining that a setting prevents the action. Also this setting does not prevent users from using programs to access local and network drives. And it does not prevent them from using the Disk Management snap-in to view and change drive characteristics.Also see the "Hide these specified drives in My Computer" setting.
Windows Components\File Explorer
User
At least Windows 2000
HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer!NoViewOnDrive
WindowsExplorer.admx