I had a similar issue the other day...
It's not possible to give more detailed errors on the front-end for security reasons but also, at the point of this fatal, none of your fields or tables even exist yet. Therefore, more detailled errors here would not provide you with the answer that you're looking for.
Have you recently removed or renamed a FK table or renamed references to it? Maybe another wizard field?
Anyway, knowing admin, I bet he's already seen this and debugging... Just in case, I'll post this to him too.
Best of luck,
Gez