A fatal error occurred in Microsoft Installer.
A file that was needed for a successful installation was not found or was inaccessible.
Error 1603 is a catch-all error used by Microsoft Installer when an unexpected failure is encountered during an installation. Quite often this occurs when a file that is needed for an installation is not found (perhaps it was deleted by an antivirus solution or it can't be accessed on a network share)
Target computer may need to reboot after applying Windows updates. In these cases Windows may not allow additional MSI installations until the target has rebooted.