Yeah, I would check the data types over time to see if it was changed at one point as well as at what point (version) it was assigned a default value of zero. Like I said I never changed or altered it and it could only have changed in one of the beta versions or something. Looks like I had (from 2008) TPv1.05beta1.zip installed and I found tp1beta4 and TP106_beta2 in my backups from 2010
so theres a few clues
but it seems it might be easier to just delete the default of 0 on install (edit the db) of TP if it exists...
Good luck, also you could just let folks figure it out since it really isn't that hard - lol