To disable hidden shared resources, which can provide certain ways to compromise your system, do the following.

Go to Start - Run, input "regedit" (without quotes), click "OK". Find the key:

HKLM\SYSTEM\CurrentControlSet\Services\LanmanServe r\Parameters

Set the value:

AutoShareServer = 0 - under Windows NT/2000 Server
AutoShareWks = 0 - under Windows NT/2000 Professional

or autorun a BAT file containing a command like this:

net share c$ /delete