I have a 1.5 GHZ G4 PowerMAc 15". It is about 18 months old. has 1.25 GHz Ram for about 8 months I been playing Americas Army for about 14 hours, when it started to freeze on me. so I let it sleep for two hours then I went back and played another hour. The whole system froze. When I start it up it goes Gray and just sits and sits. then after a few hard reboots it now shows the Apple and a Spining Disk of lines gray in color and it just sits there. The Dommmmmm sound every time it restarts Any idea wat might be happening? Are they any app that can hardware diagnose the this mac? or check the fans?