I have a 4TB WD harddrive connected externally (via a harddrive case) to my Windows 10 computer via from USB3 connection. Device Manager recognizes it as "TO Exter nal USB 3.0 SCSI Disk Device", but neither Disk Management or Windows Explorer can access it. This drive a 2nd internal drive mounted within my older Windows 7 machine which had died. Prior to that machine dying, I reformatted the drive and removed it to be used in a 4 bay external case. It did the same thing in it, so I tried it outside the four bay in a single and the same thing happens. I have tried different USB ports and computers with the same results. Is anyone able to suggest any fix to get this drive usable again? I suspect I did something to make this 4TB drive usable in Windows 7 taht mucked up its basic operation in another system. I'd hate to have to toss away a 4TB drive less than 12 months old.