I am trying to sort out a problem with a pc which often won't boot into Windows 7. Originally I ran some diagnostics which showed some errors on the hard drive, I changed the faulty drive, reloaded Windows and everything appeared to be working fine for a while. It has now started playing up again, occasionally it will boot into windows, stay on for a while and then turn off or not even boot into windows but get part way and then turn itself off. I have ran diagnostics on everything I can, memory, hard drive etc and all appear to be OK, while it is running the diagnostics which can often take an hour or so the computer stays on with no problem. As its a fresh install of windows I am assuming that should be OK but as it runs outside of windows I am beginning to wonder. I did try a new psu thinking that could be the culprit but it still wouldn't boot into windows. As I said it turns off completely and doesn't reboot as I might expect with a software issue. Has anyone any suggestions as to what may be the issue?