Ursprünglicher Beitrag von: jonathan12 ,
I had the same issue. I performed all steps recommended here, as well as on Apple's Support page "[http://support.apple.com/kb/TS1440|A flashing question mark appears when you start your Mac]," many of which is repeated on "[http://support.apple.com/kb/TS2570|Mac OS X: Gray screen appears during startup]," but, like the rest of the postings here, to no avail. However, I removed the hard drive and it showed up fine connected via a SATA to USB cable. Bought a new drive, installed it and still had the same issue. Removed this drive, and it also ran fine externally. According to dozens and dozens of people in similar situations, '''it's NOT the hard drive, but turned out to be a faulty Hard Drive Cable '''(Apple Part #922-9062). For the evidence, check out the user stories at the bottom of iFixit's [product|IF163-013|Hard Drive Cable page], as well as [http://www.ifixit.com/Answers/View/32466/Flashing+question+mark+on+startup%2C|this iFixit forum] — in addition to [https://discussions.apple.com/thread/3628282?start=0&tstart=0|this forum] on Apple Discussions, as well as [https://discussions.apple.com/thread/2648100?start=15&tstart=0|this one]. I would love to order this part from iFixit (where I first discovered this issue), but the item is listed as "Used" on iFixit — and my understanding is that this cable is a known faulty item. So its "Used" status is currently scaring the heck out of me. I wonder if iFixit can't source a new version of this item?