Network/Wired - How do you remove hidden administrative shares ?

How do I turn off hidden administrative shares in Windows XP ?
I have turned them off in most of our machines by the mothod provided by Microsoft, but some machines don't do what Microsoft says they will. I have adjusted the registry to stop recreating the hidden shares in all machines, but can't remove them in some.

My problem is that I can sit at a Linux machine and browse through the C$ drive of windows machines on the LAN. The Windows machines are all password protected, even the secret Administrator account, yet I am browsing from a limited account that does not provide the Administrator or Backups Operator password ,and can browse at will.

I consider this to be a major security problem, and my only protection until I get it fixed is my hardware firewall.

Microsoft's solution is to go to Administrative Tools / Shares and click on Stop Sharing. This works on some XP machiens, but on others there is no option to Stop Sharing, only to Refresh.

Perhaps there isn't a graphical solution, in which case I would welcome a more technical approach.

Thank you in advance for any help you can provide.

AdamV on WindowsSecurity.com provided the answer.

it is net share C$ /delete
net share D$ /delete
net share E$ /delete
net share F$ /delete
net share admin$ /delete

I have been presented with warnings about the consequences of deleting these back doors, so by all means look before you leap.

And if you leap then find a consequence greater than the security issue, you unleap by removing the one key you added to the registry.