When I tried to start up my Mac one morning It wouldn't boot, it simply gave a rhythmic groan (dundun-dun). I've tried a load of disk utilities that I had on a disc (Drive Genius 2) and I think it looks like a bad sector in the System file, of all places. I read another thread in a different forum and he told a guy to hold down command-v while booting to go into verbose to find out what the problem is. I did. In rhythm with the hard drive, the command "Disk 0s2 I/O Error" but I know that it is connected because I ran all of the disk utilities fine. One of the utilities that was, thankfully, on my tools disk (I highly recommend creating one) was Carbon Copy Cloner so I have copied everything to a USB drive which I am running on now. I have also run OS X Disk Utility once I had booted off the USB HD and I tried to repair Macintosh HD but it came up fine (I guess that was from the huge amount of disk utilities I had used!) but when I tried to repair permissions, there was a huge list of things that it repaired.
Please help, you only realize how much you rely on your computer when you can't use it.
Please help, you only realize how much you rely on your computer when you can't use it.