Is he using Windows XP?
It could still be the blaster worm.
Does he have his Antivirus program updated?
Here you can get this removal tool, that will scan his computer to see if its infected with the blaster worm, and if it is it will remove it.
Also, make him use Windows Update to update his version of windows, since this is always recommended, and there is a patch from Microsoft to prevent him from getting the blaster worm ever again.
dan