Hey, I have a late 2007 macbook pro 15" and i purchased the computer used about 2 years ago. Not sure of the history but it worked fine for over a year. I used the computer to play (WoW) and calmshell to my tv. Now when the computer is powered on it just repeatable spams the Mac chime with no display on the screen. Any help on how to troubleshoot this issue would be great.