Error “The Windows Installer Service Could Not Be Accessed” when installing or updating programs on Windows 7 or Windows Vista
When attempting to install applications you may receive the following error:
“The Windows Installer Service could not be accessed. This can occur if the Windows Installer is not correctly installed. Contact your support personnel for assistance.”
For this issue on Windows XP or Windows Server 2003 see the following article:
315346 Error message when you try to add or remove a program on a computer that is running Windows XP or Windows Server 2003: “The Windows Installer service could not be accessed”
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB2642495.