MCSA/MCSE Self-Paced Training Kit (Exam 70-270): Installing ...

Guidelines for Troubleshooting Startup Using the Last Known Good
Configuration
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Selecting the Last Known Good configuration advanced boot option starts Windows XP
Professional using the control set saved to the Registry following the last successful
logon. If you change the Windows XP Professional configuration to load a driver and
have problems rebooting, you can use the Last Known Good configuration to recover
your working configuration.
Windows XP Professional provides two configurations for starting a computer, Default
and Last Known Good. Figure 4-5 shows the events that occur when you make configuration
changes to your system. Any configuration changes (for example, adding or
removing drivers) are saved in the Current control set.
Virtual address space
Lesson 3 Troubleshooting Problems Using Startup and Recovery Tools
Map
addresses
Swap memory
contents
Physical memory
Figure 4-5 Default and Last Known Good are the two available startup configurations.
Disk
After you reboot the computer, the kernel copies the information in the Current control
set to the Clone control set during the kernel initialization phase. When you successfully
log on to Windows XP Professional, the information in the Clone control set is
copied to the Last Known Good control set, as shown in the lower part of Figure 4-5.
If you experience startup problems that you think might relate to Windows XP Professional
configuration changes, shut down the computer without logging on, and then
restart it. When you are prompted to select the operating system to start from a list of the
operating systems specified in the BOOT.INI file, press F8 to open the Windows
Advanced Options Menu screen. Then select the Last Known Good Configuration option.
Exam Tip The Safe Mode and Last Known Good Configuration options are two of the most
useful tools to try first when troubleshooting Windows startup. Enabling Boot Logging is also
useful, typically when you are having trouble locating the source of the problem.