Error message for installing software: “this installation package could not be opened.”

Hi, this error is applicable to Windows 7 only. It is mainly getting error message while installing a software.
When I tried to install Hallmark Card Studio which was bought from PC world, a continuous error message was appearing: THIS INSTALLATION PACKAGE COULD NOT BE OPENED.CONTACT THE VENDOR TO VERIFY THAT THIS IS A VALID WINDOWS INSTALLER PACKAGE. Help needed immediately.
