It is possible you may need to completely reformat and erase the hard drive to clean it. The next step would be to test the clean hard drive for errors, and replacing if it fails the test or if it still behaves the same way after erasing.
http://wdc.custhelp.com/app/answers/detail/a_id/3865/
http://wdc.custhelp.com/app/answers/detail/a_id/866/
http://wdc.custhelp.com/app/answers/detail/a_id/8/
Regards,
