Four years before I bought 500 Gb Western Digital Internal Hard disk. Now It stopped working. Using Windows 8 Pro from Dec 2013. Last two years it work's perfect. But last two months it stopped working. The OS freeze and crashes continuously. Some programs may hang including Windows Media Player and VLC also. Yesterday I installed New RAM, After installing the new ram facing the same issue. But If I install Windows 7 Its works good. Not Perfect. What can I do? I need My Hard- Disk. Cause I don't spend to anymore. Already I tried the diagnostics tools. I performed the scan. After completing scan, it shows some error. I tried to fix that, but it shows "unable to fix".