USB problem

http://windowshelp.microsoft.com/W [...] 11033.mspx

http://windowshelp.microsoft.com/W [...] 81033.mspx

Notes

When connecting a device to a USB port on a USB hub, monitor, or other device that's plugged into your computer, ensure that the USB port has enough power to support your device. Smaller devices, such as USB flash drives and mice, and devices with their own power cords, such as printers, typically work properly when connected to an unpowered USB hub. Some devices that use more power, such as USB-powered scanners and web cameras, require a hub that has its own power cord to function properly. If a device doesn't work properly when connected to a hub, try connecting it directly to one of your computer's USB ports.

Devices that transfer large amounts of information, such as external hard disks, scanners, and video cameras, function best when connected to high-speed USB 2.0 ports. Some older computers may include only USB 1.x ports, or a mix of USB 1.x and 2.0 ports. If your device requires a high-speed port to function properly, check information provided by the manufacturer for your computer to ensure that the port you're using supports USB 2.0. If your computer includes only USB 1.x ports, you can add USB 2.0 ports by installing a USB 2.0 card inside your computer.