"Dear Dr. FixIt,

Recently, my MacBook started displaying a white screen with a question mark when I start it up. Do you have any idea what is going on?"

-- Phillis L.

Hi Phillis,

The question mark on your Mac appears when the computer is unable to find a bootable partition to start the operating system with. Several things usually cause this, either some critical system files have been accidentally deleted, or your Mac’s hard drive has failed. In our experience, it’s a bad hard drive about 75% of the time that will need to be replaced to get your Mac going again.

The good news is that relative to other, more expensive repairs that Macs sometimes require, replacing the hard drive is fairly inexpensive, and can provide a good opportunity to upgrade to a drive with a larger capacity for storing more music, videos and applications. A favorite trick of mine is to hold my ear up to the computer where the hard drive is and listen to the noises that the spinning drive is making. Drives that are dying will make lots of clicking, starting and stopping, or even scratching noises. Of course, you could always bring it by one of our shops, as diagnosing broken hard drives is always a good excuse for me to break out my stethoscope (no, I’m not kidding).