Hi, I am looking to sell my iMac 2007 so I tried wiping everything off it,, I put the mac os x disk in to wipe it through that. So I used disk utility to wipe my hard drive. Then I restarted my computer but it comes up with a flashing folder with a question mark, so I put the mac os x disk back in and It says "this software cannot be installed on this computer, please help, thanks.