Application Levels:  CATIA / LCA V5R16

We are having a problem where the VPM Navigator host does not show up in the VPM Navigator Connection Window for some users on some machines.   Since there is no hosts, these users cannot connect to VPM Nav.   

The specifics

• Some users do not see the host in the VPM Navigator connection window.   As a result, they cannot connect to VPM Nav. 
• These users are able to login to VPM Nav on other machines.  Assumed to be CATSetting problem, but see debugging below.     
• Other users are able to login to VPM Nav on the problem machines.  

Debugging:

• Reset the CATSettings (using the home button in Tools...Option and also by deleting the CATSettings folder on the local machine) to CATReference Settings.  The host drop-down field in the VPM Nav connection window is still empty.    Result:  Didn't fix the problem. 
• Verified that the correct host and port are listed on the ENOVIA VPM Option Page in Tools...Options. 
• Since other users were able to login to VPM Nav using the same machine, we renamed a user's profile folder on the machine (C:\Documents and Settings\userid to C:\Documents and Setting\useridcopy) and the user logged in again.  Since Windows believed that the user was logging in for the first time, C:\Documents and Settings\userid was created.  The user launched CATIA and was able to connect to VPM Nav without any trouble.   However, when he launched CATIA the next day, the host was no longer there.  

Has anyone seen this problem before?   Does anyone know what could be causing the problem?  Does anyone know which file(s) we might be able to delete to fix the problem?