I get no such error when visiting your album, nor can I reproduce it when I set my own album for flatfile authentication. Could that be because I haven't logged in?
In any case, line 1042 of album_admin.pm is the tail end of the photo move routine and I think Mike's changed nothing there in quite a while Is your album_admin.pm dated July 3, 2004? That's the latest.
I do notice that Auto Sizing doesn't work. That's because it depends on ImageMagick. Do you have that installed?
J.J.