USB Troubleshooting Tips
Malfunctioning or missing device driver
All hardware devices need a device driver to run on a computer. If you plug in a USB device and computer prompts you for a device driver, it means the driver is either not installed or is malfunctioning. A yellow exclamation mark on USB root hub in Device Manager indicates this. Windows operating systems (version 2000 and later) come with many device drivers to facilitate equipment, thus users do not normally have to install them manually. In case a device could not find a driver in Windows, check the device manufacturer to get the latest drivers.
Malfunctioning or incorrectly-configured hardware
If a malfunctioning or incorrectly configured device is plugged into a USB port, the computer will hang. If it happens, computer must be switched off and turned back on. It will reset the bus and may solve the problem.
If the device is plugged in a secondary hub then plug the device directly into the root (main) hub to determine if either of the hubs is malfunctioning. If the device still does not works on the root hub, it could mean that the USB device is trying to draw either too much (more than 500 milliamps) or too little power (< 50 milliamps), both of which make the USB hub then become inactive. Go to the device manager and check the Power tab in USB Root Hub Properties to check how much power the device is requiring.
Outdated firmware or BIOS
Malfunctioning firmware can cause unusual problems. One of the common problems caused by malfunctioning or incorrectly configured firmware is that when you unplug and then again plug a USB device, the device becomes available but it loads itself as a second instance of the device. Firmware is the most important part for all USB devices, therefore it is important to keep the computer BIOS and device’s firmware up to date.
Incorrectly configured root hub
If a USB root hub in the device manager is displayed with a yellow exclamation mark, your computer probably has an IRQ conflict. The conflict is usually resolved by disabling the infrequently used devices from the device manager to make IRQs available for the USB port.
USB cables are available in low and high speed. If a high-speed device is plugged into a low-speed cable, it can cause signal distortion, which would result in delayed transmission, packets loss, etc. Powered hubs can also cause problems. Verify that the correct power is being supplied to it.
Disabled USB controller or root hub
It is possible that the USB controller or the root hub is disabled in the Device Manager. To enable it, go to the device manager; expand Universal serial bus controller and right-click the link containing the red X and select Enable.