"Pci.sys Is Missing or Corrupt" Error Message When You Start Windows

If you try to start your Microsoft Windows 2000-based computer, you may receive an error message similar to the following:

This behavior may occur if the Pci.sys file is missing or corrupted.

To resolve this issue, use one of the following methods.

Method 1: Restore the File by Using the Windows Recovery Console

Use the Windows 2000 Recovery Console to expand Pci.sy_ from the I386 folder on the Windows 2000 CD-ROM to the \%SystemRoot%\System32\Drivers folder on the hard disk. To do this, follow these steps:

1. Start the computer to the Recovery Console.
   1. Insert the Windows 2000 startup disk into the floppy disk drive, or insert the Windows 2000 CD-ROM into the CD-ROM drive. Restart the computer.
   2. Click any options that you have to have to start the computer from the CD-ROM drive if you are prompted to do so.
      
      The "Welcome to Setup" page appears.
   3. Press R to repair a Windows installation.
   4. Press C to start the Recovery Console.
   5. Type the number that corresponds to the Windows 2000 installation that you want, and then press ENTER.
   6. Type the local administrator password, and then press ENTER.
      
      NOTE: In some cases, the Administrator password is set to a blank password. In this case, press ENTER.
2. At the Recovery Console prompt, type map, and then press ENTER. Note the drive letter that is assigned to the CD-ROM drive.
3. Type the following at the command prompt, and then press ENTER
   expand drive:\i386\pci.sy_ c:\winnt\system32\drivers /y
   where drive is the drive letter of your CD-ROM or DVD-ROM drive, where c is the drive on which Windows is installed, and where winnt is the folder in which Windows is installed.
   
   NOTE: In the preceding command, there is a space between pci.sy_ and c:\winnt
   
   The following message is displayed:

   pci.sys
            1 file(s) expanded.
   					

4. Type exit, and then press ENTER to quit the Recovery Console.
5. Restart Windows in the usual manner.

Method 2: Use In-Place Upgrade to Restore the File

Replace all missing and corrupted files by following the steps for an in-place upgrade. This procedure is a last resort before you reinstall the operating system. The time it takes to complete the following procedure is equal to the time that it takes to reinstall the operating system. Also, you may lose some of your customized settings for the system files.

1. Insert the Windows 2000 Setup CD into the CD-ROM drive, start the computer, and then press ENTER on the first option screen to install a copy of Windows 2000.
2. Click Accept to accept the License Agreement.
   
   Setup should now detect your installation.
   
   NOTE: If the Setup program does not detect a previous installation and instead continues to the partitioning page, there is a problem. An in-place upgrade may not be possible.
3. When you are prompted to repair the existing Windows 2000 installation, press R. Windows 2000 Setup performs an in-place upgrade of the existing installation.

For additional information about Windows Recovery Console, click the article numbers below to view the articles in the Microsoft Knowledge Base: For additional information about how to perform an in-place upgrade, click the article numbers below to view the articles in the Microsoft Knowledge Base: For additional information about troubleshooting startup problems, click the article number below to view the article in the Microsoft Knowledge Base: