istarsurf

HI All,
I have a problem trying to remove istarsurf from a friends computer running windows 8.1
I have tried just about everything to get rid of it and it just wont budge, I have tried the following:

Ran virus scan
Ran malwarebytes
Uninstalled any suspicious programs
Reset explorer
Tried to delete the reg key but not showing up there either.
Ran adwcleaner- didn't find anything.

I have tried to restore pc to any eiriler point and nothing---its telling me my C;\ is corrupt but when i rum a CHKDSK there is no errors.

I have done all the obvious and now im out of options, if anyone can help me (its driving me crazy) I would apperaciate it.
Regards,
Gina.