Windows Installer error code 1618 is displayed when you try to install more than one program at the same time. For example, this can happen if you install Skype at the same time that Windows is installing updates.
To resolve the problem, before you install Skype make sure that you are not installing any other programs. If Windows is installing any updates, you can wait for the installation to finish, or end the the Microsoft Installer process manually. If this does not work, restart your computer and try again.
To end the Microsoft Installer process manually: