I had an issue for a while with tracks only playing the first few seconds then skipping to next track or powering off. Eventually I sussed out it only did in when my wife and son were in the car as well - turns out she used to pass him the remote surreptitiously and if he didn't like a particular tune he would press a button at random.

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Rory
MkIIa, blue lit buttons, memory upgrade, 1Tb in Subaru Forester STi
MkII, 240Gb in Mark Lord dock
MkII, 80Gb SSD in dock