So after some trouble shooting and HDD swapping between my (2) DNS-321's I narrowed the problem down to a 1TB WD HDD.  I left the troublesome drive in a NAS last night and finally the center light quit blinking (above network connection light).  This took about an hour.  When I clicked on the NAS it showed only the 1.5 TB drive that I knew was working just fine.  I went to the NAS web page and upgraded firmware..  No change.  I've swapped bays and same thing, only one drive shows up.
I ran the SMART check on the drives and the 1.5 TB checked fine but the other drive (1TB) hangs on 90%.  
In the status it shows both drives, serial numbers, and space available and space used.
It prompted me to format the 1TB drive when I did a reboot, so I clicked ok.  It failed to format.  I tried again and got the same error.  
So my question is..  Any way to retrieve my data using a PC?
Any ideas?  I do have backup copies between my bro and dad, so I can get it back, but figuring out what I lost is going to take a long time.  
Thanks.
Brian