MBP mid 2009, Mountain lion. Few days ago started to have lock ups and allowing nothing. Everything returned a Unknown error message, or a Your are not allowed to modify this or that cause you don't have written privileges. I decided to make a permissions repair, disk utility make it but give me a The disk must be repaired. I restarted from the recovery partition and Disk Utility told he can´t repair the disk. I assume a damaged HD. I replace it, installed clean Mountain Lion from DVD, installed iLife, restored all user data (50 gb or so) everything so quickly... and then everything became slow, a lot of beach balls, and again the same messages, a Unknown error message, or a Your are not allowed to modify this or that cause you don't have written privileges. Console send the "kernel disk0s2 i/o error" Once again restarted from recovery partition, and Disk Utility again telling Disk Utility can't repair this disk.... If I try to restart, some times it loads, but allows nothing more, same messages all the time. Almost every time that i try to restart it stalls in gray screen or show a loading bar (as the firmware loading bar) an then shut down. Any idea? Thanks a lot..