I see this post is really old, but did you ever figure out what this was? I have a 2007 as well and it sounds like I am having the same exact problem. I have a new battery and alternator is good. I was thinking that it could possibly be a dead battery in my key fob, causing it to lock me out, so i changed the battery and the key worked again. But I think maybe, i just waited long enough for it to start again. Any info you could provide would be helpful.