Bloggs, receipt not necessary. If you need to log a warranty issue do it online. All you need is the HDD Model and Serial Number. If you need help finding the warranty page just post back here with the HDD manufacturer's name.
I have had your problem on a machine that was filled with spyware/malware. I would be inclined to scan the HDD for malware, virus, rootkit etc. Malwarebytes, Hitman Pro and fairly good for malware. Rootkit scan; look for Kaspersky's tdsskiller, Malwarebytes also have one or Google rootkit scanner . Anti virus can be done through some free online antivirus scans (Google again) but I wouldn't go past the first page of results.
Once you have run the scans, run chkdsk /r again and see if that clears the drive. Make sure you run it as an Administrator (Command Prompt, right click and Run as administrator ) even if you are logged on with an administrative account.