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What is the .W40 File Extension?

.W40 File Extension Description:

The file extension .w40 is popularly identified with the earlier versions of the Microsoft Windows Operating System platform, and it is classified as a backup file format of the system. The .w40 file extension is also normally associated with the multi-boot functionality of the Microsoft Windows Operating System environment, which allows a system to use multiple versions of the operating system within a single drive of multiple partitions. The file extension .w40, which resides at the root directory, is accessed by the system during the initialization portion prior to the actual loading of the operating system. This attributes to commonly associated errors but still allows for the normal loading of the system.

Normally, the .w40 file extension can experience conflicts with other file types that will cause the malfunction of the system's multi-boot feature. The file extension .w40 is commonly attributed to the files AUTOEXEC, COMMAND, CONFIG, and MSDOS, wherein each of these files has a counterpart that carries the format type DOS. Errors experienced by the system arise from conflicts that reside within any of these files, which can be located from the root folder of the system.

The file extension .w40 is usually generated by the Microsoft Windows Operating System during the boot up process. Pprevious operating system versions that contain the files AUTOEXEC.BAT, MSDOS.SYS, CONFIG.SYS, and COMMAND.COM are renamed to the .w40 file extension format, and the OS also renames previous versions to their normal form from DOS type.

The BOOT.INI file also uses the file extension .w40 in relation to its referenced options that are associated with its command switches, implemented by developers of device drivers for testing purposes. The options loaded during the system boot up can be examined from the registry under the HKLM/ System/ CurrentControlSet/ Control/ SystemStartOptions, wherein the file extension .w40 is associated with the BOOTSECT file that directs the booting of the Consumer Windows boot sector via the Ntldr and invoking the / WIN95 option.

Author: Microsoft Corporation
Author URL:
Related Applications: Windows 95, Windows 98
Common Path: C:/


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Do you have errors with .W40 files?

The Usual Cause of .W40 files Errors to Occur:

.W40 files errors are possibly serious Windows registry errors and are caused due to a faulty registry that you should rectify immediately to prevent additional damage in other applications and/or hardware. Dangers include device damage, blue screen errors and fatal operating system crashes.

.W40 files Errors - Common Symptoms:

.W40 files error symptoms include program freezes, start up or shut down problems, jerky system operation, sluggish behaviour, screen freezing, internal speaker beeps, problems accessing documents as well as problems while installing programs.

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