Hello, I recently got my dad's old MacBook Air (the original version) because it booted extremely slow and was extremely slow after the boot as well, and he thought I might be able to get it working again. So, I made a bootable USB stick with a Snow Leopard (seemed the best choice for me, it isn't a fast machine..) installer on it. Everything seemed fine until I got to the ''choose the disk where you want to install OSX on'' part. Here it just said 'can't install OSX on this drive'. I opened Disk Utility to see what's wrong and to format the drive, but in the menu the Samsung hard drive was colored red, and it said that it was damaged and couldn't be repaired. This was some sort of ''S.M.A.R.T'' failure. So, the disappointed me clicked away, but when I got to the choose the disk part again, it worked fine. It installed OSX fine and after that and the updates it TOTALLY worked fine. It was even much faster then I expected! I was very happy with this result, but next morning (I didn't plug it in over night) it was empty so I boot the machine again. The exact same problem returned. Booting took about half an hour (not a joke) and after that it was EXTREMELY slow, and I mean REALLY slow, it took literally 3 minutes to open a finder window. Now I'm completely flustered and I don't know what to do. The hard drive could be defect, but that doesn't explain why the machine worked perfectly for one night.... I hope you're able to help me. Thanks!