I have an iMac 8.1 with SSD and Mavericks installed. Upon startup I get the flashing folder with questions mark, that tells me that it cannot boot. I have a Mountain Lion boot USB (which is actually an install disk, I think, but this should be the same, right?), and with that I checked with Disk Utility if my disk can be repaired. After verifying the disk, it tells me everything is fine with the disk. So I guess the OS on the disk is damaged. Can I use the Mountain Lion boot USB and reinstall OS X, and thereby preserve my files (settings are not most important). I do have most of my data on an external HDD, but would have some valuable files the SSD (photos, documents and bookmarks). Thanks for your help!