I usually start a repair like this with either my avg disk or my avira disk. sometimes both. I have seen a virus or malware kill an already weak HDD but that death was in the works already.
Some time ago I bought an emachines system , the whole thing for 75.00 because it was "so borked it would barely boot up." I brought it home and after removing 220 some viruses and malware it worked fine. In fact My Wife still uses it today when I did an install a few months ago said just leave windows off it just takes up space.