When you try to install/uninstall some application's, you may get warning messages like:

• "The Windows Installer Service could not be accessed"
• "Windows Installer Service couldn’t be started"
• "Could not start the Windows Installer service on Local Computer. Error 5: Access is denied."

The error messages usually appear after failed installation of MSI Package or Disabled "Windows Installer" service.

Solution Resources:
How to resolve Common "Windows Installer" Problems