Answer to: iMac (Mavericks) stuck on boot (only apple logo)Had the same problem, Macbook air/Mavericks hanging on startup with apple logo and spinning gear. Tried many solutions including the ones on this page, no luck. Finally: Boot to recovery: With computer off, press & release power button then immediately press and hold Command + "r" until recovery screen appears. Open terminal: In the recovery screen, on the top menu bar click "Utilities" then "Terminal". Type each of the following commands in terminal: "mount -uw /" press enter "chown root /" press enter "chmod 1775 /" press enter "exit" press enter Close terminal and click restart from the top menu bar. I must admit that I caused this problem myself by changing the permissions on my startup HD. Hopefully this helps.