The Pc's operating system is windows XP and I have been working on this computer for about a month. I took it apart, cleaned it out and it runs quite a bit smoother. There is only issue with it, which was an issue when I first started working on it. The USB ports are not working. When I go to plug in anything that uses a USB the computer recognizes that there is something plugged in, but it doesn't work. For example, when I plug in a mouse it will recognize it but the cursor won't move and the mouse doesn't work. I know a lot about computers, bit this one has stumped me.