During Windows 7 startup, sometimes blue screen will appear.
This usually happens due to incorrect installation of any hardware or software.
Most of the problems are caused due to incorrect software installation.
It conflicts with other programs and create BSOD errors.
One way to get rid of such issues is boot into safe mode and uninstall the conflicted software.
Still if you cannot get rid of that, you may run system restore.
This will restore your computer to an earlier date before installing that software.
Actually no, BSOD's main culprit's are driver corruptions and/or failures. That's one of the biggest reasons. Along with virus's that can corrupt inportant system files or damage them, they are both reasonable for a BSOD. Hardware I would say is a pretty general term, but it's ranked up there. Software, not so much.
You can't assume that his issue is because of bad software either, so I wouldn't get him to remove anything just yet.
If he has a system image that would be one of the best ways, it's a great feature that maybe only 10% of the windows users out there actually know about, and maybe around half of those 10% actually use it.
You can't assume it's software though. He hasn't given you any error codes from the BSOD or any dump files to prove anything yet.
I can somewhat read dump files, but I know there are better people for that on this forum that can definitely read them.