Power on your Mac while holding ⌘+ option+ P+ R until you hear the Mac chime twice, then release the keys and let it boot normally. This is often reinforced when I see entries for 'Disk I/O read/write error' or similar in verbose mode.Īssuming you don't see Disk I/O errors you might also try resetting the PRAM and/or SMC.

In my experience this often comes back to a failing/failed hard drive.

It might not give you a clear cut answer but it can surely provide some clues. Give it a minute and check to see where it's hanging. Try powering it off (hold the power button for 5-10 seconds) then powering back on and entering verbose mode using the method described above. Verbose mode displays what is happening while the Mac boots, the stuff that is normally hidden behind that gray screen with the Apple logo and spinning gear. Power the Mac on and hold ⌘+ V until you see a black screen with lines of text. When your Mac consistently hangs at the loading screen you described (Apple logo with spinning gear) the best advice I can think of is to reboot using verbose mode.