Ok, when you download MHDD and unpack the file (mhdd32ver4.6.iso) from arhive, you will get image file or ISO file ( mhdd32ver4.6.iso ).
You may use google for detail instructions or YouTube. Use sintax of words: “how to burn iso”

Why did I write all this for running MHDD tool instead of going to malware removal?
Because I believe that malware is not responsible for this harddisk behavior that you described.