after fitting a new asus a7v600 motherboard cpu and video card, my windows xp will not start. I swapped the original hard drive with xp installed, which was starting fine.but since swapping the new motherboard and bits it will not get past the black boot up screens. all it does is constantly restart. I have tried safe mode and it still does the same. I put the hard drive back in my old pc and it starts fine. am I missing something?