Microsoft Knowledge Base Article 310353 contains the following INTRODUCTION:
To help troubleshoot error messages or other issues when you cannot determine the cause of the issue,
disable common startup programs, settings, and drivers to eliminate possible software conflicts when
you start Microsoft Windows XP. This procedure is known as "clean booting." This article describes how
to perform a clean boot, how to start the Windows Installer service, and how to restore your system from a clean boot state.
Note After you follow the instructions for a clean boot, you may temporarily lose some functionality. If you restore the settings, you restore the functionality, but you may receive the original error message or experience the problematic behavior.