After a couple of mysterious wipes and some corruption of the CF card in the Bluetooth iPod, I redid the insulation and padding inside and it seems to have settled down.
While noticing pin 1 (as directed by the CF board), I noticed that the soldering on the back of it was a bit "spiky" so I've gone a bit overboard now.
Fortunately removing a spinning hard drive has left a lot of internal space to play with in the case, not all of which I've filled with new and exciting electronics.
I'm now playing music in my office from the iPod to speakers across the room and it's pretty stable!
