USB problems after upgrading Windows - It is not uncommon for USB devices to cause problems after upgrading a computer from Windows 98, Me, 2000, XP or Vista. If you encounter a problem after you upgrading, first check to see if your device is compatible. Check the Windows hardware compatibility list (HCL) and the manufacturer’s site for information regarding compatibility. You should also download and install the latest device drivers (click here to scan your PC for updated drivers). Some devices listed on the HCL don’t function properly and also there are devices not listed on the HCL which function perfectly, depending on the particular driver used. Sometimes it just comes down to a process of trial and error.
Windows won’t recognize any USB devices – When Windows XP won’t recognize any USB device, regardless of which port it’s connected to, there is likely a BIOS (Basic Input/Output System) or Windows configuration problem. Check to see if there is a configuration option on your computer where the BIOS that asks whether an IRQ (Interrupt Request) should be assigned to USB. Although the option’s actual wording varies among BIOS manufacturers, you should enable this option by setting it to either On or Yes (depending on your BIOS manufacturer and BIOS version). Otherwise no USB devices will work on XP.
Problems with XP’s USB Controller – A problem with Windows XP’s USB Controller configuration can also prevent any USB devices from working. To determine whether the USB controllers are working properly, open Device Manager and expand the Universal Serial Bus Controllers node. Beneath this node, you should see a USB Universal Host Controller and a USB Root Hub. You should see either a USB Universal Host Controller and a USB Root Hub listed for each of your computer’s USB ports or a USB Universal Host Controller and USB Root Hub for multiple ports.
Regardless of how many USB Universal Host Controller and USB Root Hub entries your PC has, if any of the icons have a red X over them, they’ve been disabled. If a device is disabled, you can enable it by right-clicking the device and selecting Enable from the resulting shortcut menu.
Also, check the driver that is being used for your USB ports. To do so, right-click on a USB component, click Properties and select the Driver tab. The Driver tab should list the Driver provider as Microsoft. The Digital Signer should be Microsoft Windows XP Publisher. If it lists anything else, you might want to update the driver. (If you have just updated the driver and started having problems, you might want to try to roll back the driver.)
If the driver appears to be OK, but you can’t seem to make any USB device function, then use the Uninstall button. This will allow you to remove the driver completely and make Windows think that the USB ports don’t even exist. Then you can go back to the System Properties sheet and click the Add Hardware Wizard button. This will allow Windows to redetect your computer’s USB ports. Normally, during the redetection process, Windows will try to enable the ports using the standard Microsoft drivers. Assuming that there is nothing physically wrong with your computer’s USB ports, this should fix the problem.
Bandwidth and power problems – Another common problem with USB devices is that you can only use so many USB devices simultaneously. This is because each USB 1.1 port is limited to 12 Mbps (megabits per second) of bandwidth (USB 2.0 allows for 480 Mbps) and 500 mA. If you exceed either of these limitations, then the USB devices will cease to function.
There is no real way of knowing how many USB devices you can use before you exceed your bandwidth limitations. There is also no monitor to examine the USB bandwidth. You’re going to have to evaluate it for yourself. Scanners and digital cameras use a lot of bandwidth because they transfer large files of data to your computer. Think about what devices are connected to your computer’s USB port, and how they are being used. If you have lots of devices connected that transmit a lot of data, you might be pushing your luck on the port’s available bandwidth.
Power consumption is a lot easier to figure out than bandwidth consumption. To figure out how much power you are consuming, there are a few things to keep in mind. First, each USB port on your computer supplies 500 mA. This 500 mA has to be shared among all devices connected to it. If you connect a single device to a USB port, power consumption isn’t a consideration, because most USB devices only consume around 100 mA.
Things start getting interesting when you start connecting USB hubs. If you connect a USB hub to a USB port, then the port’s 500 mA must be shared between the USB hub and all of the devices connected to the hub. You can also daisy chain USB hubs. If you daisy chain USB hubs together, you can have up to five hubs connected in a series. 500 mA must be sufficient to power all connected hubs and devices. A USB hub does consume power, even if no other devices are connected to it.
Many manufacturers have started making USB hubs that have an external power supply. If you have a USB hub with an external power supply, the power supply will supply a total of 500 mA to the hub. This means that if you have multiple powered hubs daisy chained together, then each hub will be self sufficient and will consume almost no power from the computer’s USB port or from other hubs in the chain.
There are still limitations though. The five-hub limit still applies whether the hubs are powered or not. The other limit is that you must still avoid overburdening any one hub with USB devices with excessive power consumption. Finally, external power sources do nothing to provide extra bandwidth. If you were to interconnect five hubs with four devices each, you could connect 20 USB devices to a single USB port, as long as none of the devices had excessive power consumption. At the same time, though, these 20 devices would have to share the 12 Mbps of available bandwidth.
Windows will actually tell you how much power your USB devices are using. This number doesn’t actually measure power consumption, but rather how much of the USB port’s power is being used. Remember that you can have powered USB hubs connected to the computer. If a powered hub is connected, then the devices will be feeding off of the hub’s power, not off of the computer’s power. Therefore, the computer will show you that there is very little or no power being drawn from the USB port.
To view USB power consumption, return to the Device Manager, right-click the USB Root Hub entry, and click Properties to display the USB Root Hub Properties sheet. Select the Power tab and you will see how much power is being drawn from the USB ports.
If a device (or a combination of devices) draws too much power, then the hub will usually turn off the port. To get the port to function again, you must disconnect the device and reattach it to the port. Depending on the type of hub that you are using, there may also be a dialog box that prompts you to reset the port.
Problems with a specific USB device – This usually an easy problem to solve. First, isolate the problem. Unplug all USB devices from the system, including USB hubs. Next, take a known good USB device and attach it to the system. If the known good device works, then you can be sure that there is nothing wrong with the port itself.
Now take the device that was malfunctioning and plug it directly into one of the computer’s USB ports while no other USB devices are connected to the system. If the device starts working, the problem most likely was that device was conflicting with another USB device. One way that USB devices can conflict with each other is if they share a common serial number. Each USB device in a system must have a unique serial number. Having two devices with a common serial number is very rare, but there are documented cases of it happening.
If the device now works and it isn’t sharing a serial number with another device, it was probably malfunctioning because of an overloaded USB hub or a conflicting device driver. The only real way to sort out the problem is to use trial-and-error by plugging in various combinations of USB devices until you find the device or devices that the malfunctioning device is conflicting with. Once you track this down, you can usually solve the problem by moving the devices to different physical USB ports or by updating the drivers for both devices.
What if plugging in the malfunctioning device without any other USB devices being plugged in doesn’t cure the problem? Try checking the computer’s Event Logs for clues to the malfunction. If the event log doesn’t give any clues, try plugging the malfunctioning device into another computer. If the device works on the other computer, then you can be sure that the device is good.
If the alternate computer is using an operating system other than Windows XP, the problem could be that the device or its driver isn’t Windows XP-compatible. Check to see if there are updates for your device for XP, if not, contact the device’s manufacturer to see if there are any known issues with using the device with Windows XP.
If the alternate computer is running Windows XP and the device is working, then I recommend checking out what version of the device driver is being used on each machine and using the one that works, even if it isn’t the most recent.