I think you hit the nail on the head. Yes I had Windows 7 Pro. After my rebuild the Pro product code was not visible, so I installed Home premium and that is when I noticed the missing CPU. My last option was to buy a new porccessor, but at £10 it did not break the bank. I have now got a new install of Windows 7 Ultimate. I will install in a few days. I have a feeling that is the problem. I had changed everything in msconfig and unistalled proccessors, I follwed everything I could find on the internet and feel a but stupid that I did not realise this. I shall confirm the install as soon as I have done it. It will be so nice to have all my cores back.