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Thanks all. I have been on the Zen site and it recommends installing a recovery program to the player- and if the computer doesn't know the player is there...? Anyway, with nothing to lose I uninstalled the driver and everything with Zen on it. No small thing as it comes with all kinds of 'are you sure, this is only for advanced...' type warnings. Plugged the player back in and it immediately recognised it and found a driver from somewhere. Seems to be OK now, and hasn't made me defect to Apple yet!