Hi there. Sorry for the ambiguous title of this topic, but I am confused by this issue myself. - I have a MBP mid2010, which is one of the fortunate generations of MBP where the DVD disc drive doesn't work. - I am using OS x 10.6.8. - I have recently upgraded it with new RAM and replacing the HDD with a new SSD. After a lot of issues installing an old OS x on a new HDD without any disc drive as well as lots of problems with the RAM, I finally got it working properly. The last couple of days I've been using an unbelivably large amount of time trying to install XCode. No matter what installer I was using, it would either not read my installer file or give me an error halfway through installing it. When it wouldn't read the installer, rebooting helped but second time I rebooted I got the grey screen when booting and a progress bar followed by another progress bar came up and then it turned itself off. (I found that other people have had the same issue and a solution was to boot from install DVD and use disc utility. Here again a problem that my disc drive doesn't work.) I then plugged in my old HDD and booted from that, and tried to verify and repair my SSD using disk utility. Here another error occurs, saying: "Error: Disk Utility can't repair this disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files." So I figured, in order to avoid any more headache, I would just buy the mountain lion upgrade from app store and install this. However, I'm in doubt, because it says that it is a requirement to have 10.6.8 or greater installed, but since my SSD is corrupt, I'm assuming that it won't work trying to upgrade it on an corrupt HDD. Wouldn't you guys agree? So my plan would be to find a complete installer of mountain lion and install it (from a bootable USB ofc.) on my SSD with my fingers crossed that the SSD is still functional. Do you guys have any advise that can ease my pain here?