Hi, i have a weird problem. I have a Mac Book Pro laptop and sometimes when i close the lid and the computer enters the sleeping mode it doesn't turn on again so i have to turn it off by keeping pressed the power button. Then when i put it back on i see the gray screen at the beginning twice. This doesn't happen always. I thought it was a virus so i formatted the computer and upgraded to Lion but the problem remains. Is there a problem with the power supply or the hard drive? Have anyone had this problem before? Thanks for your time.