windows 7 won't boot (missing/corrupt boot loader) reinstalled windows, same problem

I have a neighbor who has a windows 7 desktop, she told me it wouldn't
boot, and even after repeated attempts to repair itself (the repair
utility reports that it was successful) it still won't boot, after
several attempts to repair itself we decided to reinstall windows from
the hidden partition (she didn't get a CD or DVD with the computer).
Windows installed and booted, installed several updates, I installed
Avast, OpenOffice, Chrome, Firefox and went home. A day later the
computer is having the same problem. While I was there I made sure SMART
was enabled, so next time I'm there I"ll boot into Ubuntu from a CD and
see what SMART reports.

Is this a common problem with windows 7? Any suggestions about how to
diagnose this, if SMART is not reporting errors?

TIA,
Mike