A windows 7 laptop was dropped off in the office with an unusual problem.  Any applications which were downloaded onto the PC would fail to install if they relied on Windows Installer, such as the Australian Tax Offices (ATO) E-tax application . The error tended to indicate that the installation was corrupt. However I knew this wasn’t the case as the very same msi package would install without issue on another PC. In fact through the process of elimination I could get Windows Installer to install the msi package if the run from the command prompt using msiexec.exe.  Read more about Windows Installer fails to install msi package with “This installation package could not be opened” error …