**also posted this on Apple Support forumsbut constantly have login issues there...cannot continue that thread! The last answer on my query was that I need to re-install from DVD, but I'm living overseas and think I probably didn't bring it. Is it possible to fix using bootable external drive?** I'm on a MacBook Pro Core 2 Duo from 2010, running Snow Leopard. My computer has always been a little slow and crashed a couple times a day, probably due to working with big files. But in the last month, I think I've had Firefox-related issues, as I was constantly getting "script causing computer to run slower" errors, much more often than usual. Computer was crashing, or needed to be force-restarted, nearly once an hour. I have 3 partitions on my drive. One that is all photo and music files, one that is a small scratch disk (for Photoshop) and one that is everything else. So yesterday when it crashed again, I just figured this is the new normal for me, until perhaps someone confirms this is a Firefox error and fixes it. But that time, it didn't restart. Grey screen for a very long time. Luckily, I had just backed up everything earlier that afternoon--I'm not usually this lucky. Booted up from my external drive, and found errors on the main partition. But could not repair; was getting "disk could not be unmounted" error. Finally I force-ejected the partition and repaired it. Verified it again, everything seemed fine. Then I went to check that the startup disk would be the internal drive. Hmmm, so then I was getting error with the "bless tool." Could not select the startup disk. Restarted again, and now when I held down the option key, only my internal drive came up as an option. Strange, but I thought maybe that means it's fixed. Nope, grey screen for many, many minutes. Restarted again. This time while holding down option key, only the external drive came up. Upon starting, it said "the disk you inserted could not be recognized." I hit ignore, and yep, it was my internal drive that was no longer being recognized. So finally I reach the subject heading. Went into Disk Utility again--which just an hour ago told me everything was repaired--and tried to erase the internal drive. This is a BIG DEAL for me, as I'm constantly running out of space due to large design files and now have much more stuff on my external drives than my internal. So re-creating the internal drive isn't a simple matter of cloning the backup, but picking through to find what can fit into the more limited space. But the drive was still not appearing so....had to be erased. But it won't erase. This is what I'm getting: "Disk Erase failed with the error: POSIX reports: The operation couldnt be completed. Input/output error" What does this mean? What can I do? Naturally this would happen while I'm in the middle of a project. Please, please, please help. I don't want to be working off the external drive.