OS X Yosemite: If a flashing question mark appears

If a flashing question mark appears

A flashing question mark at startup means your Mac is having trouble locating the system software.

If your Mac starts up after a brief delay, try reselecting your startup disk. Choose Apple menu > System Preferences, click Startup Disk, then select the startup disk.

If your Mac doesn’t start up, see the Apple Support article A flashing question mark appears when you start your Mac

Last Modified: Sep 23, 2015
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