Hi, I have 2.5" external WD MyPassport 5TB (Windows7 @ MacbookAir 2015), using it for movies... It worked great since I bought it in summer, but from last week it became terribly slow and unreliable... When copying large files to a backup, speeds drop from (normal?) 70-90mbs to 2-5mbs and even 200-500kbs (?!?!), sometimes it's back to 2-5mbs or shortly to max. 70-90mbs, but mostly it's crawling at 200-500kbs, it's crazy... When I plug it in, it takes 1-2 minutes to initialize in Win7, but in OSX sometimes it doesn't at all... Currently I'm backing it up to another drive (it will take a week on speeds mentioned above), and then I will test it... I tried other drives using the same cable and USB, and they all work great... What could be the problem? I have DMDE (full version) software, is that enough for diagnostics/repair or should I get another tool? I'd like to test it first before I send it back to the seller (under warranty)... Thanks in advance! Alex