But I haven't installed anything lately, haven't updated P6, haven't opened any new libraries....

Poser opens OK (so it shouldn't be the library prefs - that tends to stop Poser before it starts - at least it did in P5, maybe its different in P6). I didn't get the error til I clicked on the "background" colour change. As far as I can recall, I also didn't change anything else and didn't change the preference at all except to errrmmm - ah. maybe.

Just re-opened Poser and now realise that one thing I did do was delete the properties window (I wanted a bigger preview area). So, of course that got saved when I exited P6...

Wonder if that's got anything to do with it?..

Cheers,
Diolma