Just do the same as I suggested for thesimbul : download
Alcohol120% and use it to make an image on the hard disk. Use the safedisc 2 setting and a read speed of 4x or lower. This will try to read the cd at a low speed, and if you can mount that image and install from it without errors, you can try to burn it back to cd if you have a safedisc 2 compatible burner.