You're welcome :)
Some programs install their own conversion add-ons, so that they convert automatically all files you copy to their proprietary format. My guess is that you installed such a program (like a picture viewer or editor, I know one that does that by default:
Spb Imageer), and then you restored your PPC from a previous backup, effectively uninstalling the program, but without removing the ActiveSync settings. Or something like that. Anyway, your uninstall was incomplete.
So ActiveSync was still trying to convert the picture using a filter that is not there anymore. You see the point.