A recently acquired hard drive - a basically new drive - appears to have been causing my mbp to shut down randomly (different drive and the problem goes away). I ran a surface scan on it using tech tool pro 5 and found just one bad sector on the drive. I zeroed the drive using the binary 0000 pattern option in tech tool (1 pass) and ran the surface scan again and this time the surface scan gets the all clear.😕 Should I be worried about the drive? Is it likely to cause the same shut downs on my mbp? I know the only way to know for sure is to try it, but I tell ya, installing a hard drive on the mbp is time consuming!!