already in the machine. (wonder what sort of machine that would be?)
Now fire it up and hold down the Option key until you see Startup Disk choices on the screen.
Choose the DVD and go from there.
This previous software disc, is it a retail copy of Mac OS X ?
If all that fails, try booting the machine with the "R" key held down.
That should launch the recovery partition on the hard drive.
Good luck
P
I ran disk utility and it said that my disc needed to be repaired. However, I forgot to do this and then I was downloading the new mountain lion software and now all I get is what looks like a DOS screen that says disc error press any key to restart. I tried puting in the software disc that I had previously and hold down the C button to hope that it would start off of the disc. However it just spits it out and says unbootable disc,disc error press any key to restart.

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