Mac OS X cannot be installed on "Macintosh HD", because this disk cannot be used to start up your computer
I have a macbook pro with snow leopard on it. I am giving it away to a family members, but would like to erase the disk before giving it away. When I put my snow leopard dvd in, and click "install", I get a screen asking me to select the hard drive to install on. When I click the only one listed: "Macintosh HD", I get the message:
Mac OS X cannot be installed on "Macintosh HD", because this disk cannot be used to start your computer
If I try to boot from the dvd, my mac just hangs on the gray screen that shows the apple logo. Basically I put the dvd in, shut down the computer, when I turn it on, I hold the "C" key, and it just hangs.
How should I go about erasing everything on the computer, and re-installing the OS, I just want it to look like it did when it came from the factory. Any help would be much appreciated.
Note: I lost my original install dvd, so I called Apple and asked for a replacement, they charged me $20 and sent the Snow Leopard disk that I am using as my replacement.
Thanks.
MacBook Pro, Mac OS X (10.6.8)