I've been having the same problems, only mine are very recent. I purchased a mac for my mother no more than 6 hours ago, and I was configuring it. I was attempting to transfer some information over with an NTFS external hard drive, since I had sucessfully opened, explored and used files on it prior. As I was doing normal browsing, I plugged it in, and got a message saying "YOU NEED TO RESTART YOUR COMPUTER NOW" right when I plugged it in. So, I reset my computer, and after that, it refused to boot. it got right to the light blue screen, and just stopped. I have tried all of these methods for fixing it, but none seem to work. I really need help on this. Thankyou.