These days I use an iPhone as my mobile music device. I have a bit over 1800 songs on it. I usually use shuffle and had it stuck in a weird state a couple of weeks ago — it was constantly playing me just a few tracks. I usually listen for just half an hour to an hour at a time, so I don't know if it would have started looping or what, but those were basically always there for a week's worth of commutes. I finally restarted the phone and that seemed to help, but what do you know, a couple of weeks, several restarts and one operating system upgrade later, it's again playing me exactly the same tracks.
As much as I love the The Roots, honestly, at this points Adrenaline!'s "Once a-again, once a-gain..." start makes me mostly think "once again indeed."