1. How to Use System Restore
System Restore regularly
captures system settings so that you can restore them later if you
experience a problem. Using System Restore to return your computer to an
earlier state should be one of your last troubleshooting steps, however, because it might cause problems with recently installed applications and hardware.
You can run System
Restore from within either the System Recovery tools or from within
Windows. To use System Restore from System Recovery tools (which is
necessary only if Windows will not start). To use System Restore from within Windows, follow these steps:
Click
Start, click All Programs, click Accessories, click System Tools, and
then click System Restore. The System Restore Wizard appears.
If
this is the first time you are running the System Restore Wizard, click
Next to accept the default restore point. Then, skip to step 4.
If
you have run System Restore previously and it did not solve the
problem, click Choose A Different Restore Point and then click Next.
On
the Restore Your Computer To The State It Was In Before The Selected
Event page, select the most recent restore point when the computer was
functioning correctly. Click Next.
On the Confirm Your Restore Point page, click Finish. When prompted, click Yes.
System
Restore restarts your computer. When the restart has completed, System
Restore displays a dialog box to confirm that the restoration was
successful. Click Close.
If System Restore does not solve your problem, you can do one of two things:
Undo the system restore
The problem might not be the result of changes to your computer at all,
but rather a hardware failure. Therefore, using System Restore might
not solve your problem. Because restoring the computer to an earlier
state might remove important changes to your system configuration, you
should undo any restorations that do not solve your problem. To undo a
system restore, simply rerun System Restore using the steps in this
section and choose the default settings.
Restore an earlier restore point
Your problem may be caused by recent changes to your computer, but the
negative changes occurred before the most recent system restore.
Therefore, restoring an earlier restore point might solve your problem.
Repeat the steps in this section to restore to an earlier restore point.
2. How to Troubleshoot USB Problems
The most common way to connect
external devices to a computer is USB. USB provides expandability
without the complexity of connecting internal devices such as PCI cards.
Connecting USB devices is so simple that most users can connect and
configure USB devices without help from the Support Center (provided
that they have sufficient privileges). However, users do occasionally
experience problems with USB devices. The following sections provide
guidance for troubleshooting USB problems.
2.1. How to Solve USB Driver and Hardware Problems
If you do experience problems, following these steps might solve them:
Restart
the computer. Some software might require the computer to be restarted
before functioning properly. Additionally, restarting the computer
forces Windows to detect the USB hardware again.
Install updated driver software, if available. Check Windows Update and the hardware manufacturer's Web site for updates.
Uninstall
the device's driver and software, disconnect the USB device, restart
the computer, and then follow the manufacturer's instructions to
reinstall the software. Many USB devices require a driver. Typically,
the driver should be installed before connecting the USB device. If you
are experiencing problems with a USB device, the most likely cause is a
driver problem. For information on how to troubleshoot the driver
problem. External storage devices such as USB flash
drives and external hard drives typically do not require a driver,
because the required software is built into Windows.
Disconnect
the USB device and reconnect it to a different USB port. This can cause
Windows to detect the device as new and reinstall required drivers.
Additionally, this will solve problems related to a specific USB port,
such as a failed port or power limitations.
Replace the USB cable with a new cable or a different cable that you know works properly.
2.2. Understanding USB Limitations
If you installed the USB
device's software correctly and you are using the most up-to-date
version of the driver, you still might have problems because of USB's
physical limitations. Limitations that can cause problems include:
Insufficient power
Many USB devices receive power from the USB port. Connecting too many
unpowered devices to a USB hub can result in a power shortage, which can
cause a USB device to not respond properly. This is particularly common
when using an unpowered external USB hub. To quickly determine whether a
problem is power related, disconnect other USB devices and connect each
USB device directly to the computer one by one. If devices work when
connected separately but fail when connected simultaneously, the problem
is probably power related. Decrease the number of devices or add a
powered USB hub.
Excessive length
USB devices can be no more than 5 meters (16 feet) away from the USB
hub to which they are connected. Although USB devices will never ship
with cables longer than 5 meters (16 feet), some users connect USB
extenders to allow longer distances. Depending on the quality of the
cable and possible sources of interference, you might experience
problems with shorter distances. To determine whether length is the
source of problems, remove any USB extenders and connect the USB device
directly to the computer.
Too many devices
USB can support up to a maximum of 127 devices connected to a single
USB host controller, which is more than enough for the vast majority of
client computer scenarios. You can have a maximum of seven layers of USB
hubs connected to the computer's USB host controller, and no more than
five external hubs.
Insufficient bandwidth Most USB devices are designed to work within USB bandwidth limitations.
However, video cameras in particular might need more bandwidth than USB
is capable of providing. If you receive a "Bandwidth Exceeded" message,
first try disconnecting other USB devices. If the message continues to
appear, attempt to reduce the bandwidth used by the device by lowering
the resolution of the camera. For best results with a video camera,
connect it to an IEEE 1394 (also known as Firewire or iLink) port.
Note:
If you see the message,
"Hi-speed USB device is plugged into non-hi-speed USB hub," the USB
device is USB 2.0, but the USB port is an earlier version. The device
will probably work, but it will work slowly. You can improve performance
by adding a USB 2.0 port to the computer.
2.3. How to Identify USB Problems Using Performance Monitor
If you are concerned that you
may have a USB bandwidth or performance problem, you can identify the
problem by using the Performance snap-in:
If
the problem you need to identify occurs when you are actively using a
USB device, connect the USB device that you want to troubleshoot and
turn it on. If the problem occurs when you first connect the USB device,
do not connect the device until after you have begun logging.
Click Start, right-click Computer, and then select Manage.
Expand System Tools, Performance, Monitoring Tools, and then click Performance Monitor.
On the Performance Monitor toolbar, click the green Add button.
In the Add Counters dialog box, in the Available Counters group, expand USB. If you are troubleshooting the failure of a USB device, add the following counters for the <All Instances> instance:
Iso Packet Errors/Sec
Transfer Errors/Sec
If you are troubleshooting a USB performance problem, add the following counters for the <All Instances> instance:
Bulk Bytes/Sec
Avg. Bytes/Transfer
Click OK to add the counters to Performance Monitor.
Performance Monitor begins
collecting data about your USB devices and connections. Attempt to
reproduce the problem (for example, by copying a file to a USB hard disk
or connecting a video camera). If you are troubleshooting performance
problems, right-click the Performance Monitor display and click Clear
immediately after you begin using the device to ensure the counters
include only data created during your test. The longer you allow the
test to run, the more accurate it will be. You should stop Performance
Monitor before your test ends.
After reproducing the
problem, pause Performance Monitor by clicking the Freeze Display button
on the toolbar or by pressing Ctrl+F. Because you added performance
counters for all instances, you probably have a large number of
counters. To browse individual counters to identify the specific source
of your problems, press Ctrl+H to enable highlighting.
Click the first counter in
the list. After you select a counter, the graph related to that counter
will be shown in bold. Examine the values for that particular counter.
If the counter shows an error, make note of the USB controller and
device causing the problem. Press the down arrow on your keyboard to
select the next counter and continue analyzing USB performance values.
USB errors should not occur
under normal circumstances; however, Windows can automatically recover
from many USB errors without affecting the user.
If you are troubleshooting USB
performance problems, examine the Bulk Bytes/Sec counter to identify
the instance that relates to the device you are using. Then select the
counter and make note of the Average value. Theoretically, USB 2.0 can
transfer a maximum of 60,000,000 bytes/sec. However, this theoretical
maximum will never be realized. More realistically, you might be able to
achieve half that value. USB storage devices are often much slower, and
performance will vary depending on the performance of the device
itself. USB hard disks typically average less than 10,000,000 bytes/sec
but can peak over 20,000,000 bytes/sec. Performance of hard disks will
also vary depending on the portion of the disk being written to or read
from, the size of the files being accessed, and the disk fragmentation.
2.4. How to Examine USB Hubs
Connecting a USB device to a computer can include several different layers:
A USB host controller, which is connected directly to your computer
USB host controllers are often built into the computer's motherboard,
but you can add them by using an internal adapter or a PC card. If the
name of the controller includes the word "Enhanced," the controller
supports USB 2.0.
A USB root hub, which is connected directly to the USB host controller Typically, USB root hubs are built into the same device that contains the USB host controller—your computer's motherboard or an adapter card.
Optionally, additional USB hubs that connect to the USB root hub to create additional USB ports
USB hubs can be external devices that you add, they can be an internal
device within a computer, or they can be built into a docking station.
You can use Device
Manager to examine the USB controllers and hubs in a computer, determine
their power capabilities, and examine the power requirements of the
connected devices. This can help you to identify the source of a USB
problem. To examine USB devices, follow these steps:
Click Start, right-click Computer, and then select Manage.
In the Computer Management console, click Device Manager (under System Tools).
In the right pane, expand Universal Serial Bus Controllers.
Right-click an instance of USB Root Hub (there might be several) and then click Properties.
Click the Power tab, as shown in Figure 1.
This tab displays the power capabilities of the hub and the power
requirements of every connected device. To determine the requirements of
any specific device, disconnect the devices and connect them again one
by one.
