Should not require you to do anything. The names.nsf, which holds contacts an groups on a local users machine, is only getting a design refresh.
Are you certain you are not changing what was once a Multi-user install back to a single user install, or the other way around, changing a single user install into a multi-user install?
I only ask because that would change where the Notes client looks for the names.nsf. Also, if you for standards reasons, change the data directory, same issue. You only need to move the names.nsf to the correct data directory and the situation would be rectified.