I assume you currently have a seagate hard drive in there. If so, download seagates hard drive diagnostic utility suite, SeaTools, here:
http://www.seagate.com/ww/v/index.js...00dd04090aRCRD
Run the SeaTools diagnostics and make sure there is a hardware problem with the drive rather than something else. This could just be a filesystem corruption problem, or some malware issue rather than a failing hard drive. If you have a seagate drive, the Seatools diagnostics are the best tool for checking the drive.