So I have a desktop Compaq Presario 7500. It is running Windows XP SP3, and will not recognize my mouse or keyboard. This problem came all of sudden, I was removing programs from Control Panel a few days ago, but I doubt that it is the cause. I can not access anything because the monitor won't activate until the mouse moves. I have tried every USB port none will work. However, the mouse and keyboard both work fine on other desktops. Thank you for your help.