I tried to do an erase and install on my macbook pro 17''. I put the first install disk in that came with the macbook pro, and everything went smoothly, it prompted me to put the second disk in, and right at the end of the install, it gives me a message saying "Install failed, try installing again," I've tried 3 times and it gives me the same message.. Do I need to buy new instal cds? Or could it be some other problem? The original install disk is 10.4. something if that...