1. Understand fully the section titled, "Using System File Checker", in the TechNet article "Chapter 27 - General Troubleshooting" concerning the use and troubleshooting strategy with this utility. In addition a very good article on the TechAdvice site is "SFC."
2. The article [Q186157] states that during the installation of a new program (including Win98), files on your hard disk may be detected and replaced with older versions, and describes the use of the Version Conflict Manager. If a newer version of a file is detected by Win98 Setup, a version conflict occurs. Prior to Win98, most installation programs (including Windows 95) prompt you to either keep the existing file or overwrite the file with the older file. When you install Win98, this prompt does not appear and newer files replaced by Win98 Setup are automatically backed up to your hard disk for compatibility purposes.
3. The article [Q192832] warns that when using the System File Checker (Sfc.exe) tool to restore a file (for example, the User.exe, Gdi.exe, Setupx.dll or Krnl386.exe file) from a cabinet (.cab), the wrong version of the file may be extracted. This can result in the inability to start Windows (for example, the computer may stop responding/hang) or a Windows Protection Error messages may be rendered. This article explains that after starting the computer, a user should extract the correct file.

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