When closing out NL220, an automatic prompt comes up asking 'Do you want to make a backup of the project
Error reading source file is a result of creating a NL220 backup while running Vista server.
There are two ways to avoid this error.
Shut down Vista server before closing down NL220 and selecting to make a backup.
With Vista server and NL220 still running, go to the menu bar and select Project > Backup project...
In the Backup a project... screen, select Backup.