I don't know if this has been seen by anyone else, and I haven't as of yet be able to reproduce it.

However, while I was in my car (no access to Serial), the player all of a sudden started switching between Radio and Player and back and forth, once every second. To verify that the remote wasn't sending strange signals I removed the battery (while driving down the highway at 60! (won't ever do THAT again)), and attempted to press some buttons on the player, which were not responsive. It did this for about a minute before I unplugged it and plugged it back in and it didn't continue.