i think i know why this is happening. each time a disc gets burnt, it generates some kind of checksum ID to identify it based on the properties of the track. because you're only burning single discs, the chances of these IDs being the same is much greater than a disc with multiple tracks so the player thinks the new disc is actually the old one and is playing the track from the onboard cache.
it's the same principle as sometimes happens by opening a Prince cd into iTunes and the track listing comes up as a Madonna album from the database it looks up from. that's my guess anyway. you should be able to test it by noting which cds this happens to and it should be something you can repeat if my theory is correct.
it sounds like the firmware needs to be tweaked to dump the cache when a disc is ejected, which is effectively what you're doing by powering off/on the deck.
