Won't let me reformat disk

Are you really ssking about 10.4 Tiger or Mountain Lion, because your profile shows one thing, but you have posted in the 10.4 forum?

Install or Reinstall Mavericks, Lion/Mountain Lion 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 ZeroData 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 Lion/Mountain Lion, Mavericks: Select Reinstall Lion/Mountain Lion, Mavericks 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.

OK. Then the above will not work on that system. Do this instead:

You will need the original installer DVD Disc One that came with the computer originally.

Booting From An OS X Installer Disc

1. Insert OS X Installer Disc into the optical drive.

2. Restart the computer.

3. Immediately after the chime press and hold down the "C" key.

4. Release the key when the spinning gear below the dark gray Apple

logo appears.

5. Wait for installer to finish loading.

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 entry with the mfgr.'s ID and size) from the left side list. Note the SMART status of the drive in DU's status area. If it does not say "Verified" then the drive is failing or has failed and will need replacing. SMART info will not be reported on external drives. Otherwise, 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.

Quit Disk Utility when the formatting is finished. At this point you can reinstall Tiger, if you wish, or leave the computer as is. Eject the installer disc before shutting down the computer.

I am running 10.6.8 and am unable to erase the HD. I tried the Command R and Option key suggestions above but to no avail.

I do not have the original disks. Any suggestions for getting this done at home or do I need to have them help me at the Apple Store? It's a large monitor and I hate to drag it in if I don't have to!

Thanks!

You need the original discs. You can purchase replacements:

Apple Store Customer Service at 1-800-676-2775 or visit online Help for more information.

To contact product and tech support: Apple - Support - Contact Apple Support.

You have posted in a two month old topic. You should not just pop in on someone else's topic for your own problem. You should create your own topic or search the forum for other topics from which you can find a solution.