ProblemYou are having problems with a USB device one or more devices stop functioning or the system hangs when another device is connected. SolutionEnsure the device driver is installed firstA majority of USB problems occur from connecting the device before Windows knows what the device is, so it cannot find or install the proper device driver. This results in the device being classified as an "unknown device" to Device Manager and it will stay there forever until corrected. To clear an unknown device:
Ensure adequate power to deviceA single USB device may draw a maximum of 500 mA or 2.5 watts from any single USB hub connection. Some hubs cannot provide enough power for one or more devices that draw maximum power. Try disconnecting all other USB devices, then connect only the problematic device to see whether it functions properly. If it does, you will need to use a separately powered hub for one or more devices to ensure there is enough power for all of them. Reset hardwareShut down your PC. Disconnect the power from all devices. Restart your PC and boot fully into Windows. Reconnect the power to your devices to allow Plug and Play settings to refresh. Use the root hubTo avoid data signal and cabling problems, if the device is plugged into a secondary hub, disconnect it from the secondary hub and reconnect it to the root hub (direct USB port) on your PC. If the device is already connected to the root hub (main system), try connecting it to a USB hub to improve power and signal conditioning. Change cablesNot all cables are created equal or are of high-enough quality to pass data signals properly for high-speed USB 1.1 or higher-speed USB 2.0 devices. Try a shorter cable or a cable from a different manufacturer. Configure the USB root hub to use an IRQ
Update your PC's BIOS firmwareIt is not unusual to learn that the BIOS that runs your PC's system board has a few kinks and flaws. Plug and Play features existed long before USB devices were invented, so the implementation of Plug and Play in your BIOS may not be up to the task of properly handling USB. Check your PC maker's web site for BIOS revisions for your system board, and download and install the latest version. DiscussionUSB technology is perhaps the most practical method for connecting peripherals ever conceived for a computer system. The number of devices that use USB has grown tremendously since its initial implementation almost anything you want to connect to a PC is available in USB versions and many items are only available in USB. USB, however, is not foolproof BIOS, USB chipsets, adequate power supply, proper cabling, and well-designed software device drivers must all work together to provide that true Plug and Play experience for everything from PDAs to video cameras and MP3 players. USB devices themselves do not often fail, so it is important to verify all of the elements that allow USB to work. The examples above are very common and reliable methods to ensure your USB devices works with your computer. See AlsoComprehensive information about how USB works with Windows XP may be found at http://www.microsoft.com/whdc/system/bus/USB/default.mspx. A general overview of USB features and functions may be found at http://www.microsoft.com/windowsxp/using/networking/learnmore/jones_02august05.mspx. |