One of my friend got a problem when booting up the Mac OSX, the computer takes a long time when booting with a blinking globe on the screen. A folder with a flashing question mark alternated with the Mac logo inside appears also take a long time (several minutes) then Mac boot up normally.
This problem happened when you select Network Disk as Startup Disk and you don’t have NetBoot servers are available. Do the following to rectify the problem:
1. Open System Preferences
2. Open Startup Disk
3. Choose the Startup Disk corresponding to your Mac OSX
4. Close & restart your Mac.