If the Lenovo Yoga 520 did not slow down, I wouldn't have got the MacBook Air. Today, I decided to revive the Lenovo Yoga 520 instead of throwing it away. How slow is slow? About 10 minutes to start up and another 5 minutes to load a program. While starting, I would see a black screen. I tried using Ccleaner to remove junk files, uninstalled some software, removed unnecessary startup applications, restart, defragged, restart again... But nothing worked. So I did this. Opened Lenovo Vantage to do a Hardware Scan. The scan tells me the 1TB HDD drive is not so good. Next, I clicked on Recover Bad Sectors. The process took more than 2 hours. What are bad sectors? A logical — or soft — bad sector is a cluster of storage on the hard drive that appears to not be working properly. ... These may be marked as bad sectors , but can be repaired by overwriting the drive with zeros — or, in the old days, performing a low-level format. Windows' Disk Check tool can also repair such bad