Chris I am as puzzled as you here. This is not something happening very often, only two people (you and @Alain22) faced something like this so far, even though tens of thousands new users per month install the app. So this is not a known issue and there is no know solution for it.
Since this is not first time happening to you, I can assume we can rule our user mistake, too improbable. So there is something with the data, and probably data syncronization. However, you did not mention this is shared archive, so again data synchronization betweem several copies can be ruled out.
However, you made a transfer of your data from old PC, so probably there was some data corruption already existed in your ini files, that is now causing issues. Thinking logically, that is the only explanation I can come up with right now.
If we take this for main hypotesis, then I would suggest you do following. This procedure will help you clear you data.
1) Separate those two people. Since you only 22 faces of your child, that would be pretty easy to do.
2) Turn on option for storing dossier file, and then immediately close the app and delete all ini files from your archive. If you happen to have any picasa ini files, delete them too, they also can be source of data contamination.
3) Start the program. Program will recreate all ini files from the scratch. And since dossier option is on, it will use different format, referencing only dossier people ID, leaving out external ID’s that are probably resoponsible for people merging.
This is all just theory, but quite a solid one.
