Windows Installer – a brief description

Windows Installer is a Microsoft technology used for the removal, installation, and “state” management of programs. Management of the state includes upgrades, resolution of configuration issues, and modification. Windows Installer consisting of three elements working in unison.

The client
This includes any application that invokes Windows Installer. This also includes “Add or Remove Programs” in the Control Pane and software distribution technologies.

The service
The Installer service is in charge of managing the stages of an installation (add, remove, upgrade, change). Copies the required files to the hard disk, makes the necessary modifications in the registry, creates shortcuts, and more.

The package
The compressed files and installation information in an “.msi” file. The file: “msiexec.exe” is launched when an application using the Windows Installer package is installed or when a restart is required.


There are prior installation frameworks (such as InstallShield and SetupAPI), but Windows Installer utilizes advanced features. These include an automated uninstall sequence and the ability to repair programs when they are first launched. It is also capable of managing shared resources and it can ensure that file version rules are adhered to consistently. Before Windows Installer, making modifications to an application such as upgrades or deletion of items could result in application failure. A failed installation of one application could cause other programs to function incorrectly. By providing consistent version rules, Windows Installer reduces these issues and provides a more reliable framework.

Issues and repairs

A central part of the Windows Installer service is the Windows Installer engine, or “msi engine”. It drives the installation of a program. With Windows XP this engine is already part of the system. For other operating systems the application automatically installs the engine or the user must do it manually. There are situation where errors arise or the Windows Installer becomes corrupted. Warning dialogs appear stating that: “The Windows Installer Service could not be accessed.” For Windows XP and later, this could be a critical issue and can mean having to repair or even re-install the operating system itself. Attempts to resolve this involve terminating previous installation processes, installing the Windows Explorer engine, or manually registering Windows Installer. We advise searching the Internet for required steps related to the first two strategies as required. To perform a manual registration:

Open Windows Explorer by right-clicking on the Start button in the taskbar and selecting Explore.
Locate the Windows System folder (typically this is C:\Windows\System32 or C:\WINNT\System32).
Locate the msiexec.exe file and take note of the path for step 5.
Click the Start button and select Run.
Type "<path>\ msiexec.exe" /REGSERVER. For example: "C:\Program Files\AppFolder\msiexec.exe" /REGSERVER
Press Enter.
There are instances of malware (“malicious software”) that can infect your computer and cause unexpected actions to occur. In one such example, the Windows Installer is launched each time the web browser is opened and it is requesting the user insert a CD to complete an installation. There are those that suspect viruses can make use of Windows Installer to initiate

Other solutions

There may be situations where you are infected by malware and you need to run your computer in Safe Mode and attempt to remove the suspect application. According to Internet sources, you can run Windows Installer in Safe Mode by doing the following:

Reboot in safe mode by restarting your computer and pressing the F8 before the splash screen appears.
From a command prompt, type:
REG ADD "HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal\MSIServer" /VE /T REG_SZ /F /D "Service"
net start msiserver

Press Enter on your keyboard.
Microsoft has a page dedicated to Windows Installer support which you can find here: http://support.microsoft.com/default.aspx?pr=wininst

They also list error codes here:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/msi/setup/error_codes.asp

It is also advisable to check your system for any signs of malware infections. Having the proper tools to solve malware infections will save you time and be less risky.

You can manually remove malware, however many malware items are sophisticated and have either propagated throughout your system or are designed to be evasive and difficult to remove. Having the proper tools to address malware infections will likely save time and be less risky. A good anti-spyware tool will have scheduling, quarantine, and backup capabilities. You will also want an anti-spyware utility such as XoftSpySE that does frequent updates and is capable of thorough scans.