Does this sound like a failing external hard drive? It works perfectly when connected, but on occassion can make a grinding/buzzing noise, unless I touch the top of it very lightly with a finger! The noise always then disappears, at least for a while. Could this be a failing drive, or one thats possibly fallen before (with its insides or casing perhaps no longer 100% in place)? It does not make a noise when lifted, so nothing seems to be out of place, and it does work ok. Thanks for any tips if possible in diagnosing the problem :) its a 500G Maxtor, a couple of years old.