Rio finally understood the issue with my broken Karma. Well... after a second go where they managed to get the model right, but not quite the problem. We eventually sorted that out and they said:

If the player is still in warranty we suggest you return the player to the point of purchase for a repair.

I think it's out of warranty - in any case, I can't find the receipt.

Rio have stopped selling the Karma but haven't yet come out with the rumoured replacement (the Chroma, due late 2005). I'm only aware of iRiver's range of players supporting Ogg-encoded tracks, but it seems they don't support gapless playback. The ubiquitous iPod doesn't do gapless either, nor play Ogg without some hacking. Plus, I hear it's sound reproduction is poor compared to the stuff from Rio or iRiver.

So... looks like an opportunity to open up the Karma and stick in an 80GB a 40gb drive