Microsoft's bid to dismiss a $521 million judgment against it was dealt a setback by the U.S. Patent and Trademark Office yesterday.

The University of California in 1999 sued Microsoft for infringing its patent, which permits the use of interactive applications such as looking at and purchasing merchandise on different Web pages, according to Trey Davis, a director of special projects for the UC system.

In 2003, a federal jury in Chicago found that Microsoft's Internet Explorer browser infringed on the patent, awarding damages to the university and Eolas Technologies, which licenses the technology. In March, the U.S. Court of Appeals for the Federal Circuit in Washington sent the case back to the Chicago court. To win at retrial, Microsoft challenged the patent's validity.

"The arguments that Microsoft is trying to make in court have been refuted by the Patent Office," Davis said.

Microsoft spokeswoman Caroline Sanderson called the decision "disappointing news."