Yes - looked at all the obvious things you mentioned (though I hadn't seen fs_usage before, very useful, will see if that shows anything up). There's virtually

Yes - looked at all the obvious things you mentioned (though I hadn't seen fs_usage before, very useful, will see if that shows anything up). There's virtually nothing installed on the box - we stream pretty much everything and it's only used as a media center style machine. I've made an appointment with the genius bar to see if they can shed some light on the issue.