California 707,
My name is jesse leonard and I work for the Dell Social Media Team. You mention that when you lock your system the headphones do not work. Thanks for pointing this out. I'll try to replicate the behavior and see if it's a simple setting miss. It sounds like you covered all the bases. So most likely I will escalate this to engineering and keep this thread updated.
Thanks,
Dell-Jesse
I've already turned in/exchanged one new laptop that had this exact issue, this is the second brand new laptop with this issue.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic