I think the 'bloody problem'
is probably a problem based around the fact that you seem to be using an 'Internal'
Hard Drive as an 'External'
Hard Drive. The difference between these two is perhaps to delecate for you to realise; but an 'Internal'
Hard Drive goes within the Computer and cannot be moved about too much and certainly not in a protective bag. An 'external'
Hard Drive is prepared to be moved about - it doesn't like it that much but it is made to do it and its safe to do it, it will go about, it has its own protective case, and is safe.
Its easy to blame the computer - but I think its probably just been worn out and is broken.