Unmountable Boot Error

Question

I have a HP Pavillion zv5000. I have had it for two years. For the past two months it was fine. I watched movies and listened to my iTunes music. It is not connected to the internet and I did not download anything. Two days ago I was charging my iPod and then clicked on the iTunes song I wanted. It then shut down. Everytime I pit the computer on it goes to the all the way to the Windows XP insignia and then a blue screen comes on and says Unmountable Boot Error and turns it self off and back on. It continues to do that without stopping. I tried logging on on the Safe Mode but it still does not go on. I cannot explain it. Help please. I just moved here and in Denver all I have is my music and movies.