I disabled it in the php code ... we need to upgrade to the new SMF anyway, and will soon. We don't even use Avatars in the Gallery, so it was doubly annoying.
Since there is no table in our SMF database called what the new Photopost is looking for, it seemed the best thing to do. I don't know whether Photopost is working with an older copy of SMF, or whether ours is the older one and RC3 will fix this error. We've got RC1.2 of SMF 2 installed. Our older PP never had this issue.