My wife was playing a game on our MacBook (2007) earlier when it suddenly froze. I couldn't kill the game using normal methods (command tab, escape, etc.) So I had to cold cut the power. When I tried restarting there was a pretty long delay (~1 minute) before the white screen came up and then nothing. Now when I restart the computer the white screen comes up like it normally did, but no apple logo and then no OS. I had a failed hard drive on the computer before so I tried putting in an install disc during boot. Nothing happened. I held alt while the computer starts and the install disc shows up, but no hard drives. When I click the install disc nothing happens. Thoughts?