1. Command Prompt
The Command Prompt option in the Choose a Recovery Tool screen opens a command-prompt interface with all the power of the command prompt environment, instead of the limited
features of the Recovery Console used in Windows XP. You can run disk
management, copy, delete, and other commands, just as you would from
within the Windows 7 GUI.
2. Using Regedit to Repair a System That Won’t Start
Another handy Startup Repair feature in Windows 7
is the capability to run the Registry editor (Regedit) from the Command
Prompt window. If you cannot start your system because of driver or
service problems or other Registry-related issues, you can use Regedit
to work on your system and repair problems.
To start Regedit from the Choose a Recovery Tool screen in the System Recovery Options dialog box , click Command Prompt. When the command prompt window opens, type regedit and press Enter.
Before making any changes with Regedit, export
the current Registry with File, Export so that you have a backup copy,
in case of problems. By default, Export saves only the current branch.
To export the entire Registry, select All in the lower-left corner of
the Export Registry File dialog box. Provide a name for the exported
Registry, such as the computer name and current date, and click Save.
You can use USB flash memory drives and other types of storage to save
the exported Registry. However, you should not save it to the hard disk,
especially if you suspect that you might need to perform data recovery
operations on it later. (You don’t want to overwrite any recoverable
data.)
Sometimes, services running at startup crash,
preventing a system from starting. Here’s how to use Regedit to disable
these services:
1. | Select the key HKEY_LOCAL_MACHINE.
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2. | Browse into the System key, and then the CurrentControlSet subkey if it’s displayed.
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3. | Browse into the services key and look for the likely offending service. Most service keys have a value named Start, with one of the following values:
| Boot driver loaded by Ntldr (Boot) | | Driver loaded at kernel initialization by Windows 7 (System) | | Driver loaded at system startup by Session Manager or Service Controller (Auto Load) | | Driver or service loaded manually from Services, Control Panel, and so on (Load on Demand) | | Driver or service that is not running or started (Disabled) |
Services with a Start value of 0 or 1 are used to boot Windows, and you shouldn’t touch them. Services with a Start value of 2
start about the same time as the Login dialog box appears in Windows.
If your Windows system boots and then promptly crashes without your
help, try setting the Start value of any suspected service(s) to 3 or 4. Be sure to write down the names of the services and their original Start values before you change anything.
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4. | Exit Regedit.
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5. | Type exit and press Enter to close the Command Prompt window.
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6. | Remove the Windows 7 DVD and click Restart to restart your system normally.
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7. | If your system restarts correctly, you’re finished!
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You might need to repeat this process a
few times, disabling a different service or two each time. In some
previous versions of Windows, this procedure required installing a
parallel copy of Windows and some loading of the old installation’s
Registry into the new system’s Registry editor, but thanks to the
integration of Regedit into the souped-up Command Prompt in the System
Recovery Options menu, that’s not necessary in Windows 7.
3. Boot Options
If you are able to start your system but it
doesn’t run properly, Windows 7 offers several alternate boot methods
that can be used to bypass a problem or boot into a reduced environment
so that you can solve the problem. For example, if you’ve recently
installed a new device driver that caused a serious system failure (you
can’t complete the boot process), you can use a boot option to boot
without that driver. (This is called the “Last Known Good
Configuration,” to be exact.)
The boot options of Windows 7 are accessed during
the early stages of system startup. If you have more than one OS on
your system, the Windows Boot Manager displays; you have until the
counter reaches zero to press F8. If you have only Windows 7 on your
computer, you’ll see a message about pressing F8 after the computer’s
own Power-On Self Test and the display of the graphical booting screen.
You have only a few seconds, so keep your finger over the F8 button and
press it when the message appears.
Note
Some systems and
motherboards include a boot menu that uses the F8 key to select a boot
drive. If your system includes this feature, check the documentation to
determine which keys to press to display the Windows Boot Manager. For
example, some motherboards require that you press F11, or F6 and then
F8, to display the Windows Boot Manager. You can also try pressing the
spacebar after the BIOS loads to access the Windows Boot Manager. |
Pressing F8 at the correct moment reveals the Advanced Boot Options menu, which contains several boot options, listed in Table 1.
Table 1. Advanced Boot Options
| Option | Description |
|---|
| Repair Your Computer | Runs the Repair Your Computer scans. |
| Safe Mode | Starts
Windows 7 using only basic files and drivers (mouse, except serial
mouse devices; monitor; keyboard; mass storage; basic video; default
system services; and no network connections). |
| Safe Mode with Networking | Starts Windows 7 using only basic files and drivers, plus network connections. |
| Safe Mode with Command Prompt | Starts
Windows 7 using only basic files and drivers. After you log on, the
command prompt is displayed instead of the Windows desktop. |
| Enable Boot Logging | Starts
Windows 7 while logging all the drivers and services that were loaded
(or not loaded) by the system to a file. This file, called ntbtlog.txt, is located in the %windir%
directory. Safe Mode, Safe Mode with Networking, and Safe Mode with
Command Prompt add to the boot log a list of all the drivers and
services that are loaded. The boot log is useful in determining the
exact cause of system startup problems. |
| Enable Low-Resolution Video | Starts
Windows 7 using the basic VGA driver. This (640×480) mode is useful
when you have installed a new driver for your video card that is causing
Windows 7 to hang or start and lock up halfway into the initialization
process. The basic video driver is always used when you start Windows 7
in Safe Mode (Safe Mode, Safe Mode with Networking, or Safe Mode with
Command Prompt). |
| Last Known Good Configuration (advanced) | Starts
Windows 7 using the Registry configuration information that Windows
saved at the last shutdown. Use this option only if you strongly suspect
that a program has written incorrect or damaging information to the
Registry. The Last Known Good Configuration does not solve problems
caused by corrupted or missing drivers or files. Also, any changes made
since the last successful startup are lost. If this option does not
help, start your system with the Windows 7 DVD and run System Restore
from the Startup Recovery Options menu. Select a recent restore point to
reset your system’s configuration. |
| Directory Services Restore Mode | Valid only for domain controllers. |
| Debugging Mode | Starts Windows 7 while sending debug information through a serial or USB cable to another computer. |
| Disable Automatic Restart on System Failure | Windows 7 can be configured to restart the system automatically if a STOP error occurs. This behavior can make it difficult to determine the cause. Use this option to disable automatic restart; the STOP error stays onscreen, so you can record the error and research a solution. |
| Disable Driver Signature Enforcement | Windows
7 can be configured to prevent the installation of unsigned device
drivers. However, in some cases, an unsigned device driver might be the
only way to get a system running again. Use this option to enable you to
install and use unsigned device drivers if your configuration normally
blocks them. |
| Start Windows Normally | Boots
the system without altering the normal boot operation. Use this option
to return to normal booting after you’ve made any other selection from
the Advanced Boot Options menu. Selecting this option causes the normal
boot to occur immediately; you are not returned to the boot menu. |
After
you’ve made a selection from the Advanced Boot Options menu, the system
boots using the startup option you selected. If you want to run the
Windows Memory Diagnostics Tool before starting your system with Windows
7, press the Esc key to display the Windows Boot Manager.
If you installed Windows 7 as a dual-boot with an
older version of Windows, the Windows Boot Manager displays both
options. Use the up and down arrow keys to highlight the version of
Windows you want to boot, and press Enter.
Whether you have a dual-boot installation or only
Windows 7 installed, the Windows Memory Diagnostic option appears in
the Tools menu on the Windows Boot Manager screen. To boot Windows 7
after running the Windows Memory Diagnostics Tool, press the Tab key to
highlight Windows Memory Diagnostic and press Enter.
Using Safe Mode, you can start your system with a
minimal set of device drivers and services. For example, if a newly
installed device driver or software is preventing your computer from
starting, you might start your computer in Safe Mode and then remove the
software or device driver from your system. Safe Mode does not work in
all circumstances, especially if your system files are corrupted or
missing, or your hard disk is damaged or has failed.
Tip
If a symptom does not
reappear when you start in Safe Mode, you can eliminate the default
settings and minimum device drivers as possible causes. |
In general, if you’ve just performed some
operation that caused a system failure, the best first reboot action is
to use the Last Known Good Configuration. If that fails to resolve the
issue, use Safe Mode. If the problem is specific to the video drivers
(or you suspect that it is), you might want to use Enable Low-Resolution
Video instead of Safe Mode. If you’ve just recently changed video
drivers or the video card itself, you might want to use the Enable
Low-Resolution Video mode if things don’t act normally during the
reboot.
When you are able to access the system through
Safe Mode, you need to resolve the issue that is causing the boot
problem. In most cases, this requires you to reverse your last system
alteration, application install, driver update, and so on. If your
system stops booting properly and you did not make any changes, you
should probably call Microsoft tech support; they might help track down
the culprit and get things back on track.
If
none of these boot options results in a repaired system or enables you
to boot the system, you mightneed to reinstall the operating system.
