If you don't have a USB cradle, then to start identifying the cause of this - you'll need to get yourself an I.D.E. USB caddy.
You then need to open up the DMS (unscrew it, it's a very simple operation) and carefully pry it open. From there it should be reasonably self-explanatory how to swap the disk inside into the USB caddy.
Plus the USB caddy into the PC and then hopefully you'll be able to see two new 'drives', one labelled PHTSYS and one labelled PHTDTA.
Both should contain a bunch of files.
If one or other is not mounting correctly, then you have a problem with the disk.
If they do, then the chances are it may just be a small corruption on the PHTSYS side (known to happen) and we have tools that can help deal with that situation.
Whatever you do DO NOT delete ANY of the partitions without using our specialised tools, otherwise if your box is not hacked - you are going to be stuck getting it fixed!