Description:
Prevents users from using My Computer to gain access to the content of selected drives.
If you enable this setting, users cannot view the contents of the selected drives in My Computer or Windows Explorer. Also, they cannot use the Run dialog box, the Map Network Drive dialog box, or the Dir command 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
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.