I don't know but SketchUp 2013 shouldn't have done anything with your SketchUp 8. As I said before, SU 2013 is installed in an entirely different directory than SU8. As far as I know SU 2013 doesn't even look at the Google folder or its contents during install. Or did you use a custom install location when you installed SketchUp? Is SU 8 in a folder called Google?