i had the damaged disk, cannot reair message pop up. and i had read another article telling me to plug an external hard drive into my computer, go to disk utility and partition it, and back everything up onto it. wipe the hard drive on the computer, then install mountain lion. after that re install everything off the external hard drive using migration assistant. and im not sure if i just got extremely lucky, and ive only tried it once but i plugged an external hard drive attempted to format it, but was unsucessful. it would not let me access it in the disk utility. but being bull headed i attempted to install mountain lion anyway. with the external hard drive still plugged in. IT WORKED! like i said i dont know if i got lucky and it just worked, or if i tricked my computer into thinking something was different. but it was super easy.
1. plug in external hard drive.
2. go to mountain lion installer
3. still select hdd for your laptop or desktop (not your external hard drive)
4. complete download.
now im not sure of everyone elses problems, but mine just gave me the error. i didnt lose any information from my lap top. when my laptop restarted it booted up just fine.
i really hope this works for everyone. good luck.