Hey, A few weeks ago my MBP (13 in, 2.26GHz Core 2 Duo, 160GB HDD, 4GB RAM, OS X 10.6.2) was telling me that I was unable to save to my internal HDD because it was "full or write protected". After a restart, I was able to save. About an hour later I encountered the same problem. I restarted again only to have my system hang up at the screen with the apple logo and the spinner at the bottom. I let it sit for nearly 20 min and it never booted. I attempted a disk repair, permission repair, reinstalling the OS, erasing the drive, partitioning the drive, booting in safe mode, fsck, and restoring from a time machine backup without any success. In verbose mode, I kept getting a "disk I/O error". I ended up installing the OS on an external USB drive and booting from that and everything worked fine, leading me to believe that the internal drive was dead or dying. My laptop was under warranty so I called up Apple and informed them of the situation. I sent them my laptop to get repaired. I had it back in a few days. I looked at the service report that was in the box and saw that they replaced the internal HDD with a new one with 10.6.1 on it. It also said that my mac passes all hardware diagnostic tests. I booted up my laptop and it failed to boot up. Again, it was getting stuck at the screen with the apple logo and the spinning gear. I tried all of the things that I tried the first time (see above) with not success.I checked and I was still getting a "disk I/O error". I don't think that the internal drive is failing because it's brand new and I can boot from my external and use finder to navigate through the files on my internal drive (and even open them up). I am completely out of ideas. I plan on calling Apple back up but would like to see if anyone online can help seeing as Apple was unsuccessful the first time. It appears that the drive is functioning properly but I can't boot from it.