"Sam" as a username

I have a friend for whom I put together a computer with Vista Home Basic on
it. She is not very computer savvy, and relies on me for support. She
"suddenly" began having all sorts of problems that I couldn't explain. (The
one that made her call me was that the computer was asking if she wanted to
format her DVD... even the Vista installation DVD.) I thought it was a
communications problem between her and myself, so I had her bring her
computer to me so I could look at it. Sure enough, it was doing what she
said. I saw that she had the Google toolbar installed, and after I was sure
she didn't use it I tried uninstalling it. It didn't work. After further
investigation, I determined that she couldn't delete files, either. Nor
could she run anything that had the User Account Control on it. I
double-checked, and she IS the only administrator account. After lots of
dead-ends and talking to her, I found out that her son had changed the name
on his account to "SAM" about the same time she started having problems. I
didn't think much about this, but as I was going over this in my head, I had
a flash.... SAM ... Security Accounts Manager Service.

Just wondering.... Could this be the source of my friends problem? Or
should I look elsewhere?