Automatic Hidden Shares
When networking has been installed on a Windows NT machine, it will automatically create hidden shares to the local disk drives. The shares are normally accessed via \\server\c$ and \\server\d$ depending on the drive letter. It is possible to disable the sharing at run-time, but this tweak will stop the automatic sharing altogether.
Open your registry and find the key below.
Create a new DWORD value of either 'AutoShareWks' for NT Workstation or 'AutoShareServer' for NT server. Then set the value to equal '0' to disable automatic sharing. If the values already exist then modify them to change the value.
Restart Windows and the automatic shares should not be created.
Value Name: AutoShareServer, AutoShareWks
Data Type: REG_DWORD
Data: (0=disable, 1=enable)