I have a problem with my iMac. If it had been shut for a while, when I turn it on, the hard disk makes a noise.. It's just like the noise a car makes when it can't start. If I wait I see a grey background and a folder with a "?". It turns on when I shut it down and turn it on several times. It takes 10 minutes some times.. I reinstalled the system, but it didn't resolve the issue. Just wanted to know if someone here has known the same problems? Is it a serious problem and what are my options? Thanks!