Well so I was messing around 1 day on my computer and it was running really slowly so I looked at the long list of processes and assumed that that must have been the problem. I ended up accidentally closing microsoft explorer and right after that the only thing left on my screen was my background. We've replaced the hardrive and reinstalled windows and yet it still makes this clicking noise that comes from the tower whenever you turn it on, and it will never even make it to the windows screen or anything, only to a blank black screen, but the computer is on. Any suggestions? I don't know all the specs, just know that it's a Hewlett Packard and it's 5 years old. It has 256 megs of RAM and the old hard drive was 40 gigs, and it had a Celeron processor.