That's too specific (one game only) to be the laser. I'd still go with the media. Actually, I think it's the burn.
What prog are you using for burning? Tell ya why I ask... sounds to me like you've selected "ignore read errors", and you've been unable to get a clean read from the first disc, which was so badly scratched. I've used DiscJuggler in the past, and if it encounters a read error, it inserts a dummy patch (all 0's) until it find the next readable sector. My suggestion... get a brand new master of this game, not a copy of a scratched copy.
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Oshawa modder... up there in Canada.