This means that your internal hard drive is not currently bootable. That can happen for a variety of reasons, which are:
Without knowing the model of your Mac, I can only guess what is going on here. To know for sure, you need to locate your original Apple software restore CD/DVD -or- a retail Mac OS X install DVD.
- The disk has crashed and is no longer usable.
- The Mac OS X System Folder has become damaged due to permission problems, a botched software upgrade, or some other software-caused problem.
- The hard drive controller on your Mac's logicboard has failed.
Do the following:
At this point, if your hardware is intact and you have a filesystem problem, the safest thing to do is to go find a firewire drive big enough to install a copy of Mac OS X on it (anything larger than 10GB should be fine), install Mac OS X to the firewire drive and then try to mount your internal hard drive while running from Mac OS X on the firewire drive. This assumes that you have files on the internal drive that you don't want to lose. If this is not the case, you can safely reinstall Mac OS X on your internal drive and start over again.
- Power on the Mac, insert the bootable CD/DVD.
- Hold down the power button until the mac turns off.
- Hold down the "C" key on the keyboard and press the power button to turn the unit on.
- It will take a while, but your Mac should start booting a copy of Mac OS X off of the CD/DVD.
- Once booted into the Installer, locate the menubar at the top of the screen. Click on the "Apple" icon (top left of screen) and click "About this Mac". Click the "More Info..." button.
- You should now see the Apple System Profiler.
- On the left panel, locate "ATA" or "Serial-ATA". You should have one of them contained within your Mac. When you click on the correct one, you should see the list of hard drive controllers (two), one with your CD/DVD rom listed, and the other with your hard drive listed underneath. If you don't see two controllers, one or both of your hard drive controllers have failed and you need to send the Mac to Apple for hardware repair.
- If you DO see your hard drive listed, then you hardware is at least working. That rules out a failed hard drive controller and mostly likely your hard drive is physically intact. The software on it might still be wrecked, but the hardware appears to work.
- Close "System Profiler" and get back to the MacOS X Installer. Click on the "Tools" or "Utilities" on the top of the menu bar. Locate "Disk Utility" and launch it.
- Within Disk Utility, locate your hard drive on the left side of the screen, click on it once to highlight it and then click the button "Verify Disk". This will do an exhaustive search against your drive to see if there are any problems with the Mac OS X installation. If there is still a copy of Mac OS X left to salvage, this will tell what the problem is.
- If "Verify Disk" finds an instance of Mac OS X with problems, you can try running "Repair Disk" and then "Repair Disk Permissions" to clean up any problems with the copy of Mac OS X. Keep in mind, when you have filesystem problems, sometimes fixing the problems can make permanent changes to your filesystem that have unintended consequences.