Web Client Network and Terminal Services Missing

When I view the Properties of My Network Places and select Advanced Settings
from the Advanced menu and select the Provider Order tab, all that shows
under Network Provider is Microsoft Windows Network. Web Client Network and
Terminal Services are both missing.

This computer is a Windows XP 32it SP2 machine authenticating with Active
Directory. The WebClient services is started and no errors appear in the
Event Log.

When I use SharePoint 2.0 and try to view a Document Library's Explorer View
I get an error stating "Cannot find 'file://" ... "Make sure the path or
Internet address is correct. I believe this error is caused by the fact the
Web Client Network is not listed as a Network Provider on this machine as the
SharePoint Explorer view attempts to use WebDav.

Other XP SP2 on the same local network do show Web Client Network and
Terminal Services listed.

What is wrong with this machine?