The LonWorks Interfaces Applet which is installed in the Windows Control Panel requires Microsoft .NET Framework 3.5 to run.
The OpenLDV 4.0 or OpenLDV 5.0 installer silently checks if .NET Framework 3.5 is already installed on the PC. If not then the installer will install the .NET Framework. If .NET Framework is already installed, the OpenLDV installer doesn't check if the .NET Framework is working properly.
So if the LonWorks Interfaces doesn't open then check if .NET Framework 3.5 is installed and running on your PC. Your IT person should be able to help you.