- Malfunctioning or incorrectly configured hardware
- Malfunctioning, incorrectly configured, or missing device driver
- Mismatched cabling
- Out-of-date firmware or basic input/output system (BIOS)
- Improperly configured root hub
Malfunctioning or Incorrectly Configured HardwareTypically, if you plug a malfunctioning or incorrectly-configured device into a USB port, it causes the computer to stop responding (hang). In the majority of these instances, you must physically turn off the computer and turn it back on to reset the bus. Note that it may be more difficult to identify which device is malfunctioning or is incorrectly configured. If another computer that you know is working correctly is available, try to plug the device into that computer to see if 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.
For additional information about how to use Device Manager to troubleshoot hardware issues, click the article number below to view the article in the Microsoft Knowledge Base:
Check the Power tab in USB Root Hub properties to check the power usage of the USB bus.
Malfunctioning, Incorrectly Configured, or Missing Device DriverWhen you plug in a USB device, the computer should load and then configure the device without ever requesting a device driver (assuming that the device falls within the defined and supplied class drivers). If the computer prompts you for a device driver, check with the manufacturer of the device to determine if a driver is available.
Mismatched CablingThere 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.
Verify the entire 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 of the devices down the chain to be suspended. If the hub is a powered hub, verify that the power supply for that hub is configured properly.
Out-of-Date Firmware or BIOSThe key to all USB devices is the firmware. The USB device's firmware contains all of the information about the device. A port is not reset until all of the descriptors in the firmware have been loaded and verified by the root hub. This is critical because it applies to items such as printers and modems. Make certain that you have the most up-to-date firmware that is available for both your computer's BIOS and each individual device.
The symptoms of malfunctioning or incorrectly configured firmware might be unusual. Typically, when you remove and then re-add a USB device, the device simply becomes available again. However, the device may appear as a second instance of that device, and load itself as such in Device Manager. If you see duplicates of a device, verify that you have the most up-to-date firmware for that device. This issue is common with USB printers and modems. A similar issue that has the same cause occurs when a device loads a device driver and then adds a second device for which there appears to be no driver. The second device is displayed with an exclamation point in a yellow circle in Device Manager. The device may work correctly, but you cannot remove the "ghost" device until you unplug the parent device that seems to have generated the ghost device. Also, you may be able to resolve this issue by updating the firmware or the device driver for that device.
Incorrectly Configured Root HubUSB controllers require that an IRQ be assigned. The IRQ line is assigned in the computer's BIOS, and usually IRQ 9 is assigned.
Issues Specific to Windows 98
Issues Specific to Windows 98 Second Edition
Issues in Both Windows 98 and Windows 98 Second EditionFor additional information, click the article numbers below to view the articles in the Microsoft Knowledge Base:
Issues Specific to Windows MeFor additional information about issues that are specific to USB support in Windows Me, click the article numbers below to view the articles in the Microsoft Knowledge Base:
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