So, here's the deal. I have a four year old Macbook that's not in the best of shape, but it hasn't failed me like this before.. ever. I installed a new security update yesterday morning along with the new iTunes, and it worked alright for most of the day. Around 10:30 or so, it just shut off. I tried to turn it back on and was faced with the gray apple logo and the horrible spinning icon. I've tried booting it up in safe mode, verbose mode, and even resetting the PRAM, and nothing works! The stupid screen stays on for HOURS. No, I'm not kidding... hours. It eventually did go to a blue screen after maybe three or four hours, (I fell asleep so I'm not sure) but it still wouldn't let me do anything. Any help? Please?