Thanks for those useful links. I did try to right click online in disk management, but cant remember the outcome. It was not helpful anyway.
The good news is that I did manage to get the drive working again by accident.
When ever I tried to to initialise this drive in disk manager on a Win 8.1 PC, it gave the error message:
“data error (cyclic redundancy check)”. So I simply uninstalled it, then plugged it back in a Win XP PC, where it showed up as normal again with all files intact. Might be a lucky fix or a disk on its last legs!
I tried HD Tune pro version 5.50, but it just crashed everytime I tried to select this drive. For a couple of seconds it would recognise the model as Scorpio, then crash. Their support was also fairly unhelpful.