27" iMac Hangs On Reboot

Question

I've got a 27" iMac 2.93Ghuz Intel Core i7 running 10.7.2.

Anytime I reboot (like for some software updates), it gets stuck at the gray startup screen (no Apple logo). If I press and hold the power, turn it off, then turn it on, it boots as normal.

Any idea why a cold startup works but a warm reboot always hangs? Any idea how to diagnose it?

Answer 1

Actually, looks like it was a disk problem of some sort. Ran disk utiity and did "Verify Disk." It said it was in need or repair.

I rebooted and went into the Recovery Mode (holding Cmd-R at boot).

Opened disk utility, selected "Repair Disk" and it repaired the boot drive.

Seems to be better now. Whew!

Answer 2

Try a verbose boot and see if the text output during the boot sequence provides any clues.