I have two Mac G5's just over a yerar old which suddenly refuse to startup in the morning after being turned off over night. When I power up my G5's they go through the process where the CPU powers on, continues to hum and spin the hard drive, but does not complete the cycle, all I get is a blue monitor, after 2 to 3 hard starts by pressing the power button on the front, and it usually works the third time. I am running 10.4.11 . I have not added any new peripherals or other software. Any thoughts.?. thanks....