I run windows xp on a hewlett packard pavilion 500 and when i boot up the computer i get a black screen that says windows did not load successflly. and gives me options of safe mode or others to start in. no matter what option i select it acts as if it is going to start as usual but then it takes me to a blue screen and then back to the black screen with the safe mode options. i can not get the pc on passed this at all. could it be a virus?