Hi. My system is Dell OptiPlex 740, 2.50 GB RAM, Win7 Ultimate 64bit. All of a sudden - the USB ports (all 7 of them) stopped to function properly. Each device I plugged into the port - got recognized as 'uknown device' and doesn't function at all. One of the biggest problems that this cause me - I can't plug in the keyboard and the mice - I don't have PS/2 ports in this computer. Thing is, even out of Windows, the USB doesn't work. I'm suspecting this because the PC giving me 'Keyboard fault' everytime I restart. So I can't got to BIOS either. Right now I'm using special combination of USB hub attached to one of the ports, and the peripherals connected to the hub. I'll be very happy to know what's the answer to my problems.. TY in advance.