Quick View in NT Workstation

A customers computer (using Workstation (SP5)) can not disable Quick View for Word documents. They have unchecked the correct box, and then go to open a web based file and Quick View is used, so the file is opened in IE. They go back to the tab andthe check mark is back. Any help on how or why this would happen. It also is a machine specific problem, not happening on all the workstations.