Hi, I was 10.7 user, I decided to upgrade to 10.8. Consequently I purchased the installer through App Store. The installation was crashing due to apparent disk errors. I did try running Disk Utility but wasn't able to fix the errors, I was getting the same message about errors not being fixable. The installation was giving me an option to install to the old 10.7.5 system. Unfortunately, the option was bringing me back to the installer. So after repeated attempts to reboot my Mac, where the only thing that I was getting was the 10.8 installation (installation was stating up automatically after rebooting). I figured out that I should try to make a different partition active. Unfortunately that did mess up the Mac completely. The laptop would boot up to the question mark sign (no bootable driver found). I found an old DVD with 10.6.4 installation does not even see my old partition. Disk utility finds it but does not allow me to mount it or make any actions to this partition. Is there a way I could fix this? I would like to boot to my old partition with 10.7.5 without loosing the data.