Okay, IPC it is.

Microsoft Knowledge Base Article - 241808
Problem Attempting Remote Administration with Local Users and Groups Snap-in
http://support.microsoft.com/?ID=241808

Microsoft Knowledge Base Article - 95900
INFO: Interprocess Communication on Windows Platforms
http://support.microsoft.com/?ID=95900

Microsoft Knowledge Base Article - 314984
HOW TO: Create and Delete Hidden or Administrative Shares on Client Computers
http://support.microsoft.com/?ID=314984

NOTE: To avoid a security problem, you may need to delete the IPC$ connection once you are done administering.

Microsoft Knowledge Base Article - 816113
HOW TO: Use Registry Editor to Restore Administrative Shares in Windows Server 2003
http://support.microsoft.com/?ID=816113