Code runs flawlessly in DEV and QA. Fails only in Production :-/

Identical configuration in prod?

Yup. Code does have that tendency. Check the logs, config because the config on the dev/test would have evolved over a period of time but you'd want everything to be in prod from day 1. It's likely that there's something amiss there.

Yes.

I had the opposite problem. I almost killed QA