USB+Problems


 * USB Problems **

This article describes advanced troubleshooting tips for universal serial bus (USB) devices in Windows XP.

If you have a problem with a USB device, try these methods first:
 * If you have a problem with a USB device, try these methods first: Unplug and the...**


 * 1) Unplug and then plug in the device.
 * 2) If the computer prompts you for a device driver, read the information that was included with the device, or visit the manufacturer's Web site to see whether a driver is available.
 * 3) Run Windows Update to obtain the latest fixes for Windows XP. When this is complete, plug in the device to see whether it is installed correctly.

If the problem persists after you try these three methods, you can use the "Advanced troubleshooting" section to try to resolve the issue.


 * Advanced troubleshootingThis section is intended for advanced computer users. If...**
 * Advanced troubleshooting**

Because USB devices are Plug and Play devices, there is little that you can do to control or configure them. However, you can trace most USB problems to one of the following conditions:- You can use the following troubleshooting tips to check for each of these conditions to help you resolve USB device issues.
 * Malfunctioning or incorrectly-configured hardware
 * Malfunctioning, incorrectly-configured, or missing device driver
 * Mismatched cabling
 * Out-of-date firmware or basic input/output system (BIOS)
 * Incorrectly-configured root hub

Typically, if you plug a malfunctioning or incorrectly-configured device into a USB port, it causes the computer to stop responding (hang).
 * Malfunctioning or incorrectly-configured hardware**

In most of these instances, you must physically turn off the computer and turn it back on to reset the bus. Be aware that it may be more difficult to identify which device is malfunctioning or is configured incorrectly. If another computer that you know is working correctly is available, try to plug the device into that computer to see whether you encounter the same issue.

If the device is plugged into a secondary hub, unplug the device from the hub, and then plug the device directly into the root hub.

Many hardware problems (such as high or low power, bandwidth shortage, malfunctioning or incorrectly-configured firmware, and so on) can cause issues to occur.

Check Device Manager to be certain that the root hub is functioning correctly. If the root hub is displayed with an exclamation point (!) in a yellow circle.

Verify that the BIOS is assigning an interrupt request (IRQ) to the root USB controller. This is required for the device driver to be loaded.

If no devices work when you plug the devices into the root hub, verify that the power requirements of the bus are not being exceeded. USB devices can draw a maximum of 500 milliamps for each connection. If a device tries to draw more power than this, the specification recommends that the computer should be able to disable that specific port until the computer power is cycled (this is known as "suspending" the port).

In addition, if the device draws less than 50 milliamps, the port never becomes active.

Check the **Power** tab in USB Root Hub properties to check the power usage of the USB bus.

There are two types of USB cables, high speed and low speed. Low-speed cables differ from high-speed cables primarily in their shielding. If you plug a high-speed device into a low-speed cable, you can cause signal distortion over long distances.
 * Mismatched cabling**

Verify the USB chain is working correctly to be certain that a device that requires the ability to draw power from the hub is not plugged into the chain on the other side of a non-powered hub. This causes that hub and all devices down the chain to be suspended. If the hub is a powered hub, verify that the power supply for that hub is configured correctly.

USB controllers require that an IRQ be assigned. The IRQ line is assigned in the computer's BIOS, and usually IRQ 9 is assigned.
 * Incorrectly-configured root hub**

To remove and reinstall all USB controllers, follow these steps:
 * Remove and reinstall all USB controllers**
 * 1) Click **Start**, click **Run**, type without the quotes “**sysdm.cpl”**  in the **Open** box, and then click **OK**.
 * 2) Click the **Hardware** tab.
 * 3) Click the **Device Manager** button.
 * 4) Expand **Universal Serial Bus controllers**.
 * 5) Right-click every device under the **Universal Serial Bus controllers** node, and then click **Uninstall** to remove them one at a time.
 * 6) Restart the computer, and then reinstall the USB controllers.
 * 7) Plug in the removable USB storage device, and then test to make sure that the issue is resolved.