Dear Sir, You said the HD was 8 years stored, did you know that
any Magnetic-Field surrounded that HD will Affect it. !!!
Will may changes the Bytes stored on it, in a way or another ,
which when read by the head will say something else ..!!!
So, you could had accumulated Magnetic-Field effect on that HD from ,
may-be a Speaker system which is Behind it, under it, any way arround
it, Microwave Oven, strong static-field,. My opinion now is that you
BackUp every thing in it to a new HD, if it is Important to you,
and save that HD in safe place, & from time to time connect that HD
to the Computer to discharge any Mag.Stat.Affect on it.
GOD Bless You .