Service, Protocol, and Adapter Lists Can Appear Blank in NCPA

• Microsoft Windows NT Workstation version 4.0
• Microsoft Windows NT Server version 4.0

SYMPTOMS

When starting the Network Control Panel tool (Ncpa.cpl), the lists of Services, Protocols, and Adapters installed can all appear blank.

The ODBC tool is also affected in a similar way for the same reason.

CAUSE

A new registry key has been added under HKEY_LOCAL_MACHINE\SOFTWARE, and the user currently logged on does not have read rights to this key.

When the Network Control Panel tool starts up, it scans HKEY_LOCAL_MACHINE\SOFTWARE for "Manufacturer" keys (for example, Microsoft). It then looks at registry keys under each Manufacturer key for "Product" keys (for example, Tcpip). Once it has found a product key it looks for a version key (for example, CurrentVersion) and then a key called NetRules. If it finds a key called NetRules it assumes that this subkey is defining a network component that it needs to be able to configure.

However, NCPA assumes that it has read rights to all Manufacturer and Product keys. If it gets an access denied error at any time while scanning these keys it terminates the scanning process and just uses the information it has already procured. This means that if a third party adds a key under SOFTWARE that is alphabetically before 'Microsoft,' and it has restricted rights applied to it, then NCPA is never able to retrieve the list of Network components from the registry and presents a blank list.

RESOLUTION

Ensure that if it is necessary to restrict access to any data in a key under HKEY_LOCAL_MACHINE\SOFTWARE, the key is placed at least three levels down the tree from this point.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 4.0. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.