recuva won't scan my hard drive...?

I choose recuva to scan the local disc C:, but I only get a message saying: failed to read boot sector. :huh:

I had a problem with my windows some time ago, so a friend of mine fixed that, it's possible(/likely) that he did something with the boot (boot.ini etc.)

anyone have any tip?

I would like recuva not only to work on my memorystick but also on the hard drive.