The Windows Installer is a Microsoft service that is responsible for installing softwares as well as uninstalling them.Microsoft Windows Installer service is a built-in feature in Windows 2000, Windows XP,Windows  2003 and Vista. With it, developers is able to reduce all cost to efficiently build and configure applications for Windows systems.
If the windows installer service is stopped or damaged you  will get an error message , “Windows Installer Error 1720 / 1722,” every time you try to install or uninstall a certain software. Normally the original MSI installation files will be cached in the 'C:winntInstaller' directory before installation is started. Improper caching of an MSI file is one of the main causes of the error also.

But  How to solve Windows Installer Error 1720? Read more