I don't know why it's not recognizing your disk.  That seems a little weird.

If you register your serial number on impulse, you can download the game from their servers and install that way.  It's probably your best alternative if the disk won't work.  If you're still having problems after that, support@stardock is your answer.

I have Sins on a CD Altaux so that is not always the case

I do know that the collector's edition has a music CD also, make sure that you have the right disc

Also maybe the disc is damaged, has been known to happen

In the end, your best bet is here

www.impulsedriven.com

download, install, register serial number, download Sins, never worry about Impulse again (unless you need to update)

It's still possible he has a DVD version and is using it in a CD drive.  In which case, either upgrade or use Impulse.