The fact that your friend can install it properly makes it a bit weird, but..
whenever I had a cd that had too many scratches on it, which gave problems with installing, I used CloneCD to make an image of it, and then installing it. CloneCD was able to make a proper image out of an inproper CD.
But the last time I did that was a year or 2 ago. It's always worth a try though.
We may have years, we may have hours, but sooner or later, we push up flowers.