My Book keeps losing drive letter

I have reformted the thing several times, but as a quick format and the normal format (took several hours).  Nothing.  When I try to run scandisk it never even starts and I get an error saying windows was unable to complete the disk check.

When I try to use SmartWare to do some type of diagnostic, it doesn’t even see the drive.  I get this error :No writable WD SmartWare partion found even though after assigning it a drive letter I can read and write just fine.