The only other place it was ever noted besides the board and the UBB CP was on the interior home page at http://www.smgfan.com/index1.html, where on a few occasions a single image appeared in place of the entire page. In that case, it would also show a random image.

Apparently a lot of people now have checked code all over the site and not found any problems. My guess is it's a Microsoft bug that hasn't been identified yet.