An irritating error message appears every time I try to install software on my computer system. It is not merely happening with one application but with all. I have tried to install Adobe 9, Google Earth, etc. etc., but at the end of the installation process, an error message occurred which says,
This installation package could not be opened. Verify that the package exists and that you can access it. or
contact the application vendor to verify that this is a valid Windows Installer package.