By default, Windows NT and Windows 2000 share every drive (with share names C$, D$, etc.) and the Windows directory (with share name ADMIN$) when the system is booted. Although
these shares are only accessible to members of the Administrators group they can compromise security because it is not uncommon for systems to have
an insecure local-administrator password.

You can remove these shares permanently by editing the registry:

• Log on as an administrator.
• Run the Windows NT registry editor (Click on Run on the Start Menu and type regedit).
• Locate HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
  Services\LanmanServer\Parameters.
• If you are using Windows NT Server change the registry value "AutoShareServer" to 0 (zero). If this value does not exist create a new DWORD value using the New menu command on the Edit menu.
• If you are using Windows NT Workstation change the registry value "AutoShareWks" to 0 (zero). If this value does not exist you need to create it as above.
• Reboot and the shares will not be recreated.

Note that Microsoft Systems Management Server and some network backup
software rely on these shares - check
that they are not required before deleting them.