One day I turned on my iMac with my 1TB WD Ext HDD (WD Elements Desktop) connected and a small window popped up saying (The disk inserted was not readable by this computer) with the options of (Ingore and Eject). Before that, my HDD worked perfectly well and I used it almost daily. I looked into my Disk Utility and saw the HDD was being read, but on the title it says (2.2 TB WD EXT HDD 1021 Media). When I select it, it doesn't let me verify, repair, erase, partition, RAID, or restore it. BTW I'm running a 20-Inch iMac late 2006 model. I don't know whats wrong with it and I have valuable stuff in there. Is there any way I can save all of those files or is there any way of fixing this issue?