Not able to boot from install disc

try booting it 2x in a row. If your boot DVD is pre Lion then do it.

Go to the App store and download the Lion installer from your purchased section. Make a bootable USB install media using

http://liondiskmaker.com/

Then boot from that media and format the HD.

If you know the DVD is bad you can call apple and for a nominal price order replacement DVD

You can also clone your existing HD to an another drive using the free SuperDuper software and boot from that and erase the original HD

What disc exactly are you trying to boot from? Is it appropriate for your Mac?

Exactly what model Mac do you have?

"Full Retail" 10.6. DVD may contain 10.6.0 or 10.6.3, and is white with a silkscreened picture of a Snow Leopard. Gray discs are model-specific, and will NOT boot a different model.

Your keyboard must be attached directly to a USB on the chassis, not on a display or other Hub. The best way to boot is to hold the Alt/Option key at Startup. Your mac uses built-in software to draw a gray screen, then over the next several minutes draws an Icon for each potentially-bootable Volume it finds. No stored information is used in this process -- everything is discovered anew.

If you bought it new three years ago, your dual 2.4GHz Quad-core is a Mac Pro 5,1 Westmere 2010 model. It shipped with custom 10.6.4 , and will not boot from any "Full Retail" discs. You will need to find the original gray discs, or order a replacement "original software" replacement disc from Apple support.

That Mac will run the latest Mac OS X, and should be useful today.

Laura Moss wrote:

I am trying to securely erase all data on my Mac Pro...

...The old machine is unable to boot from the install disc...

Is there another method to securely erase data?

Since you're currently running 10.7.5, there should also be a Recovery Partition on your HD which can be accessed and booted from either by booting with the Cmd-R keys held down or with the option key held down to invoke the Startup Manager, with which you can pick the Recovery partition to boot from.

Either way, if you buy and format a USB Flash drive for Mac use (GUID Partition Table and Mac OS Extended (Journaled)), and then boot into Recovery, you have the option of reinstalling Lion, but make sure that the Flash Drive is the target. Once that's done, you can boot from the Flash drive and repartition the internal HD. Then, since you want the old Mac Pro to be usable, you need to install an OS on the newly wiped HD, so, since there should be a Recovery partition on the Flash drive too, boot into that and once again install Lion with the internal HD as the target. Be sure to get a sufficiently large Flash drive (Staples is selling 16GB's for under $5 and 32GB's for under $9 so don't skimp); you can even throw in the bootable Flash drive as part of the sale if the "new" Mac is the 2013.😉