I have a 15.4 in macbook pro, intel core 2 duo 2.2 GHz 2 Gb RAM 120 GB HD and i bought it almost a year ago. i purchased leopard for christmas and installed it. i also bought a western digital 500 gb mybook to use with time machine. since around that time, my computer sporadically will refuse to turn off. everything will run as if it is going to turn off, and then the screen goes blank and the computer stalls and will not shut off. the num lock and caps lock keys do not light up by my lap fan keeps running. to turn it off i have to hold down the power button for five seconds. does anyone else have this problem? i already brought my laptop to the apple store and they sent it to wherever and it still has been doing this. i also ran a series of hardware resets that the tech line gave me.