• Msdos.sys

  The Msdos.sys file contains basic information about the location of the Windows folder, startup files, and other options. You can edit some of these options on the Advanced Troubleshooting Settings tab in System Configuration Utility. Additional information about the Msdos.sys file.

• Config.sys

  The Config.sys file is provided for backwards compatibility with MS-DOS- based and earlier Windows-based programs. The Config.sys file may not be present on your computer. The Config.sys file loads low-level MS-DOS-based drivers, and many of the files have a .sys file extension.

• Autoexec.bat
• Winboot.ini

  The Winboot.ini file is a temporary version of the Msdos.sys file that may be present on your computer if a program is making changes to your computer that may affect the boot process. Typically, the Winboot.ini file is deleted after the program is complete, resides in the root folder, and overrides settings in the Msdos.sys file.

• Winstart.bat

  The Winstart.bat file may not be available as a check box on the General tab in System Configuration Utility. The Winstart.bat file is created for programs that need to run an MS-DOS-based program to enable functionality of a Windows-based program. Most users do not have this program.

• System.ini

  The System.ini file contains information about your computer's settings for specific hardware. This file must be present in the Windows folder for Windows to start. The System.ini file is used to load various drivers including sound and video adapter drivers. The System.ini file may also contain additional 16-bit drivers for hardware does not use 32-bit drivers.

  When you click to clear the Process System.ini File check box in System Configuration Utility and restart your computer, the following changes occur:

  • Your display is set to a resolution of 640 X 480 pixels with 16 colors. If you had the display set to a higher resolution, program shortcuts on your desktop may overlap.
  • Your sound card no longer works correctly.

• Win.ini

  The Win.ini file contains information that is specific to the overall appearance of Windows. The Win.ini file must be present in the Windows folder or it is re-created by Windows, is read at startup for backwards-compatibility with Windows 3.x, and many of the settings are duplicated in the registry.
  When you click to clear the Process Win.ini File check box in System Configuration Utility, a generic version of the Win.ini file is created.

• Wininit.ini

  The Wininit.ini file is used to complete the installation of various components for Windows and third-party products. Each time that a program needs to copy or remove a file that is in use, instructions are written to the Wininit.ini file. Windows checks for the presence of the Wininit.ini file during the boot process and, if found, performs the instructions. Rename the Wininit.ini file with a .old file extension to troubleshoot behaviors, if the Wininit.ini file is present.

• System.dat

  The System.dat file is one of two registry files that are required to start Windows. The System.dat file is similar to the System.ini file, and contains computer and software settings. The Load Startup Group option contains the entries that are loaded from the System.dat portion of the registry.

• User.dat

  The User.dat file is the second of two registry files that are required to start Windows. The User.dat file is similar to the Win.ini file because it contains information about how to run specific programs and information about the overall appearance of Windows.

You can use System Configuration Utility to create a backup copy of the startup files.