Error: "InstallScript engine is missing from this machine. . ." when installing Symantec AntiVirus 8.0

Article:TECH99898  |  Created: 2002-01-05  |  Updated: 2010-09-07  |  Article URL
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Technical Solution



When you install Symantec AntiVirus, you see the error message "InstallScript engine is missing from this machine. If available, please run ISScript.msi or contact your support personnel for further assistance."



This problem has been reported to Symantec Technical Support. At this time, the exact cause or contributing factors to this problem have not been determined. This document will be updated when new information or a solution is found.

The following steps may resolve the error and allow Symantec AntiVirus to install successfully.


    Register IDriver.exe
    1. Click Start > Run.
    2. Type the following and click OK:

      "C:\Program Files\Common Files\InstallShield\Driver\7\Intel 32\IDriver.exe" /regserver
    3. Restart the computer.
    4. Reinstall Symantec AntiVirus.

    Reinstall the Windows Installer (Windows NT/2000 only)
    1. Delete the InstallShield\Driver folder located at:

      :\Program Files\Common Files\InstallShield\Driver
    2. Unregister the Microsoft Windows Installer file (Msiexec.exe), by typing the following at the Run line:

      c:\winnt\system32\msiexec.exe /unregister

    3. Delete the following files:


      Note: If you cannot delete these files, restart your computer in Safe mode and delete the files in Safe mode. See the References section of this document for more information on restarting in Safe mode.
    4. Download and install Microsoft Windows Installer v 2.0.
    5. Run the Isscript.msi file from CD1. The location is:


    6. After you have run the script, proceed with the installation of Symantec AntiVirus.

    Solution if McAfee antivirus software was previously installed
    If you have ever had any version of McAfee antivirus installed on this computer, check the root directory of the boot drive for a file named Program (just "Program" without an extension). This file is often left behind when the McAfee product is uninstalled and can cause this error to occur. Delete or rename the file, and Symantec AntiVirus Corporate Edition 8.0 should install normally.

    Solution for computers without a drive C
    If you are installing Symantec AntiVirus Corporate Edition 8.0 to a computer that does not have a C drive, you may encounter this error. Follow the steps below to resolve the problem:
    1. Click Start, click Run, and then type cmd in the Open box, and click OK. A command prompt appears.
    2. Type subst c: : and then press Enter.

      Note: Replace with the letter for OS drive.

    3. Install Symantec AntiVirus Server or Client to the OS drive. Do not install Symantec AntiVirus to the substituted drive C.
    4. Restart the computer.
    5. To remove the temporary virtual drive C, go back into a command prompt, type subst c: /d and then press Enter.

Error: "1920 Service Defwatch failed to start. Verify that you have sufficient privileges to start system services"

Error: "Error 1920: Service Norton AntiVirus Server..." appears when installing Norton AntiVirus Corporate Edition client

For additional information on starting in Safe mode, see the Microsoft Article How to Start a Windows-Based Computer in Safe Mode - Article ID: Q180902


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