I'd try the CKP sensor like 'DOC says. I've seen LOTS of them fail without setting codes. Drive authorization is probably OK. If the engine cranked and started but then stalled immediately or, cranking was interrupted, I'd look closer at DAS. If DAS intervention occurs a code is set (P1570). Another thing worth checking is whether or not any other failures occur (interior lights, wipers, etc.) when the engine won't start. I've seen ignition switches play some nasty tricks in the past as well as the circuit 15 relay (I think it's k12). Go with the CKP sensor first though. It's the most likely culprit.