How to Fix the "Windows Installer Service could not be accessed" Error in Windows 7 ?

Have you tried to install a program in Windows 7 that uses an MSI file as its installer and instead you saw the "Windows Installer Service could not be accessed" error? Never fear. There is an easy solution and we’re here to help you with it.

First, click on the Start menu and select Run. In the Open edit box on the Run dialog box, enter “cmd” (without the quotes) and click OK. The Command Prompt window displays. For 64-bit Windows, type the following at the prompt and press Enter.

%windir%system32msiexec.exe /unregister

This unregisters the msiexec.exe file in the C:Windowssystem32 directory.

NOTE: We will show you the commands to enter for 32-bit Windows at the end of the article.

Type the following at the prompt and press Enter.

%windir%system32msiexec.exe /regserver

This re-registers the msiexec.exe file in the C:Windowssystem32 directory.

Type the following at the prompt and press Enter.

%windir%syswow64msiexec.exe /unregister

This unregisters the msiexec.exe file in the C:Windowssyswow64 directory.

Type the following at the prompt and press Enter.

%windir%syswow64msiexec.exe /regserver

This re-registers the msiexec.exe file in the C:Windowssyswow64 directory.

To close the Command Prompt window, type “exit” (without the quotes) at the prompt and press Enter.

Reboot your computer. You should now be able to install programs that use MSI installer files. To fix this problem in 32-bit Windows, open the Command Prompt window as described above. Type the following commands in order, pressing Enter after each:

msiexec /unregister msiexec /regserver

Exit the Command Prompt window and reboot your computer to complete the fix.