iMac will not complete start-up

Recently the power to the house went off and on maybe 5 or 6 times in a row.

Now my intel iMac fails to start up. It was on at the time.

I get the doing and the grey start up screen with the spinning graphic. Then a grey progress bar appears. This is new. After some time and only a little progress it gives up and the progress bar starts again. After more time and not much progress it now gives up completely and shuts down the computer!

Would anyone have any suggestions or possible fixes?

Try booting in safe mode. To do this, hold shift at start up. let us know what happens.

Thanks for the suggestion. Gave it a try but no change.

Could the power supply be damaged by the many voltage spikes??

Could the power supply be damaged by the many voltage spikes??

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It very likely is damaged. Always use an UPS with a desktop computer in order to protect it from spikes and brown outs. I'm not talking about a surge protecter, but an UPS (uninterruptible power supply).

Strongly agree with chscag (though I know that's not much help in the immediate situation). UPS units deal with BOTH times of damaging power flucuations: too much (surge) AND too little (brownout).

If the computer seems otherwise undamaged, perhaps all that's happened is that the directory got corrupted because it was writing as the brownouts were happening. If so, Disk Warrior ($100) should be able to fix that, but without being able to tell it may not be worth the money. Maybe a local tech has a copy they can run for you for a more modest fee?

This is one of those situations where a bootable backup would come in handy. If you have your original system DVD, you can try booting from that and running Disk Utility from the menubar (choose English as your language [or whatever] and then look to the menubar for Disk Utility. Do NOT reinstall the system, at least not at this point). Run Disk Utility and see what it has to say, it might even be able to fix the issue.