I can see from reading here that it is a common occurrence. I've only had that happen before when not allowing the HDD enough time to properly boot before trying to operate the unit.
It happened after - my wife by her own admission - was hurriedly and repeatedly swapping from one function or play mode to another in fast succession (including deletion), so I'm hoping it was more a case of the hdd getting hot than it is on the way out.
It recovered after leaving the mains unplugged all night (20min at the time wasn't enough altho' the top of the machine didn't feel hot at all)
I still like this machine having only bought it new a couple of years ago - end of stock - for £160, I suppose it would be wise to have a clone of the HDD made is it easy to take out?