iMac will not start.
Started while I was using computer. Screen grayed out and note popped up saying I needed to shut down and startup the computer using the power button on the back.
Get usual startup sound and white/gray screen, and then repeating three warning tones. Nothing else. Tried using startup disk with "C" button to no avail.
iMac (24-inch Mid 2007), iOS 6.1.3