Disabling 'simple file sharing'

Right click the Start menu
->Explore->Toolbar->Tools->Folder options->View>
scroll down until yoou see 'use simple file sharing' and deselect it.
Click 'okay'
Now, you should see the Security tab on the folder.
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Windows Vista Networking & Sharing
Use access control to restrict who can use your files
HDD Share names will not stick
Cannot change default administrative shares