ITunes :: Stop Playing, Even Though The Song's Title And Counter Were Still Showing

Ok, a few months ago, I posted a problem concerning songs from my ipod that, when played in my car through the car's integrated cable, would suddenly stop playing, even though the song's title and counter were still showing on the dashboard screen. This happened with a 3 year old ipod. After taking the car into the dealer, they found no problem. Subsequently, when driving a loaner or rental, the same thing would happen when the ipod was hooked up with a Belkin cable. So, I bought a new ipod. Guess what? It still happened, AND in other cars. So then I bought a new car (not for this reason; it was just time!), and it still happened, BUT...now it's doing it when I have my iphone bluetoothed!! The songs playing are coming from my iphone, which is connected to the car through bluetooth. So, my thoughts are leaning toward something wrong with my songs, in itunes. This happens inconsistently, and not necessarily with the same songs. 

I've already spoken to 2 different people at Apple, spending hours on the phone.