Drive Wiped

Here's an interesting question. I had a customer bring me an Inspiron 1501 notebook. Told me he had a virus. I turned it on and got the no boot device msg. Reinstalled Vista. No problems. Then I used recovery software (active bootand recover my files) to find lost files. There was nothing. It was like it was a brand new hard drive. I dont think this customer has the knowledge to low leval format. Any ideas on how this might have happened? I have never heard of a virus that wipes a drive.