Can't erase hard drive in disk utilities

Are you booted from the drive you wish to erase? If, that is why you cannot do anything. If you wish to erase the drive you must boot from the Recovery HD.

Install or Reinstall OS X from Scratch

Be sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.

Boot to the Recovery HD:

Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.

Erase the hard drive:

1. Select Disk Utility from the main menu and click on the Continue button.

2. After DU loads select your startup volume (usually Macintosh HD) from the

left side list. Click on the Erase tab in the DU main window.

3. Set the format type to Mac OS Extended (Journaled.) Optionally, click on

the Security button and set the Zero Data option to one-pass. Click on

the Erase button and wait until the process has completed.

4. Quit DU and return to the main menu.

Reinstall OS X: Select Reinstall OS X and click on the Install button.

Note: You will need an active Internet connection. I suggest using Ethernet if possible

because it is three times faster than wireless.

This should install the version of OS X that you had installed.

If you have access to the original 10.4.x install DVD or a later 10.5.x, 10.6.x retail DVD you can boot and erase. If not get a clone program and make a bootable clone of your drive to boot from and erase the original.

https://bombich.com/ Carbon Copy Cloner runs on Mac OS X. We offer a free 30-day trial so please try before you buy!

http://www.shirtpocket.com/ Free Trial You can try our products for free on as many computers as you wish. The unregistered versions have limitations that are removed once you register the software.

If you are running Lion, then you have a Recovery HD, so recovery protocol does work even on your 2007 machine if you don't have to repartition the drive. But apparently you didn't read the reply thoroughly or you just don't really understand recovery using OS X since Snow Leopard. You can't tell me none of the suggestions work since i only provided one suggestion that you obviously haven't tried.

But if you wish to insist, then do this:

Clean Install of Snow Leopard

1. Boot the computer using the Snow Leopard Installer Disc or the Disc 1 that came

with your computer. Insert the disc into the optical drive and restart the computer.

After the chime press and hold down the "C" key. Release the key when you see

a small spinning gear appear below the dark gray Apple logo.

2. After the installer loads select your language and click on the Continue

button. When the menu bar appears select Disk Utility from the Utilities menu.

After DU loads select the hard drive entry from the left side list (mfgr.'s ID and drive

size.) Click on the Partition tab in the DU main window. Set the number of

partitions to one (1) from the Partitions drop down menu, click on Options button

and select GUID, click on OK, then set the format type to MacOS Extended

(Journaled, if supported), then click on the Apply button.

3. When the formatting has completed quit DU and return to the installer. Proceed

with the OS X installation and follow the directions included with the installer.

4. When the installation has completed your computer will Restart into the Setup

Assistant. After you finish Setup Assistant will complete the installation after which

you will be running a fresh install of OS X. You can now begin the update process

by opening Software Update and installing all recommended updates to bring your

installation current.

5. If you are planning to sell or give your computer away, then do the following:

After you reformat your hard drive and reinstall OS X, the computer restarts to a

Welcome screen and asks you to choose a country or region. If you want to leave

the Mac in an out-of-box state, don't continue with the setup of your system. Instead,

press Command-Q to shut down the Mac. When the new owner turns on the Mac,

the Setup Assistant will guide them through the setup process.

Download and install Mac OS X 10.6.8 Update Combo v1.1. Good luck. Please read before deciding this doesn't work either.

Then this means you have no Recovery HD for some reason. What is your problem with Lion? You can make a bootable clone if what you want is a clone of your current system. You will need an external hard drive that is partitioned and formatted for OS X. But you need a Recovery HD to do that or you must use another method - Carbon Copy Cloner 4.0.6. You can make a bootable clone using CCC, and, CCC can create a Recovery HD for you both on the clone and on your regular drive.

Why do you want to erase your current system?

OK. Do you have any bootable OS X disc - 10.5 or later? If you do, then boot from it if you can and use it to erase the drive. Before you do this please follow these instructions:

1. Deauthorize your computer from iTunes, if applicable.
2. Back up your data using Time Machine or other backup methods for OS X Mavericks or Mountain Lion.
3. If you use Find My Mac or other iCloud features on this Mac, complete these steps:
1. Back up your iCloud content.
1. Choose Apple Menu () > System Preferences, then click iCloud.
2. Deselect the Find My Mac checkbox.
2. Sign out of iCloud. When you sign out of iCloud, you're asked whether you want to remove iCloud data from your Mac. Removing iCloud data in this way makes sure that the data isn't also removed from any of your other devices that are using the same iCloud account.

Drive Partition and Format

1. Boot from your OS X Installer Disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Utilities menu.

2. After DU loads select your hard drive (this is the out-dented entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.

3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Apply button and wait until the process has completed.

4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.

5. Set the format type to Mac OS Extended (Journaled.) Click on the Security button, check the button for Zero Data and click on OK to return to the Erase window.

6. Click on the Erase button. The format process can take up to several hours depending upon the drive size.

Steps 4-6 are optional but should be used if you wish to do a security erase that will permanently prevent your data from being recovered.

If you can't find a disc to use then you need to spend $20 to buy a Snow Leopard DVD from Apple: You can purchase Snow Leopard through the Apple Store:Mac OS X 10.6 Snow Leopard - Apple Store (U.S.). The price is $19.99 plus tax. You will be sent physical media by mail after placing your order.

When you sell the computer be sure to include the Snow Leopard DVD for the next owner to use.