HP Pavilion a465c Desktop computer with a P4SD-LA motherboard won't read USB devices or media cards. This is the case with the ports on the front and in the back of the system. The usb devices get power, that is, the light in the mouse or flash drive comes on but the device is not recognized. I have performed a repair install of Windows XP, have run virus scans, malwarebyte, combofix, taken the RAM out one stick at a time and tried several different usb devices with no luck. I updated the BIOS, checked to see if the ports were disabled and even uninstalled and reinstalled all usb drivers. I am at my wits end. Please advise.