If you have any custom computers, arcade games, and hand held games take a look at those. Looking at the lot object dump, nothing jumped out to say it was custom made, but you may have some not showing in the lot object dump. Two other areas to check are your custom careers and custom foods. I've got some other ideas, but these are the usual suspects.
Run HCDU (
http://www.simwardrobe.com) if you haven't already and attach the results.