The Hitachi hard drives are our least favorite... and have been trouble for four years or more. We can generally trust the S.M.A.R.T tests, but HD Tune is better... the Free HDTune 2.55 is very limited, but at $35, the terrific 3.50 is just priced too high.
But you should figger out why it is "busy with something..." as that does not sound like a typical failure in the middle of happening.