Follow these steps to resolve this issue:
- Archive the previous QuarkXPress Installation and move it to different location on your machine.
- Download the QuarkXPress 7.5 Full Installer from the Quark Website at the following location: http://downloads.quark.com/Details.aspx?fid=119&&mid=1
- Un-stuff the installer in a new folder.
- Run the QuarkXPress 7.5 Installer; it will prompt you to either install Evaluation Version or Full Version.
- Select Full Version, type in your Validation Code, and complete the Installation process.