In admin menu, clicking on 'Groups', it says that group 'Guests' should be renamed to standard name 'Anonymous' (red cross next to it). I click it and apply the modification. Now the new name is displayed correctly once in answer page. Next time I click on 'Groups' in admin menu, the group again is called 'Guests' and it again recommends to rename it. And so on.
I recently updated my CPG from 1.4.x to 1.4.16.
Link to my gallery: http://pics.timos-welt.de
Help much appreciated.
It's a known problem.
Doesn't mean much though - regular members will never see the group names, so this is basically a cosmetical issue. No need to worry in terms of functionality.