My mac froze and wouldnt startup because it was forced to sleep while a complex program was running, and simply ended up on a blank grey screen, and this happened upon every startup. so then i tried to use a safe boot but this ended me up on the startup utilities thing. i have realised that none of the options: restore from time machine backup, reinstall osx mountain lion, and repair disk are available to help me startup, and i cant select a startup disk either as it says none are available. so i am stuck on this program and it reapears every time i restart or shutdown and reboot, so i cant do anything. Please is there any way i could either quit startup utilities or get back to my computer desktop as i have lots of non-backed up image and video files that i cant afford to lose. please help!