Microsoft defeated a major patent licensing firm in a lawsuit over technology that helps computers boot up faster Thursday.

The suit, filed in the U.S. District Court for the Eastern District of Texas, charged Microsoft with infringing on U.S. patent 5,933,630, which was issued in 1999 to Acceleration Software International Corp. The suit asked the court to award the patent holder US$2.50 per copy of Windows XP sold in the U.S. By Microsoft's account, that could have amounted to $600 million to $900 million.

Microsoft argued that there are many ways to improve the boot speed of PCs and that XP uses different technology than that in the patent.

The jury found that Microsoft did not infringe on the patent and that the patent is invalid because it was obvious and because the technology already existed. In addition, the judge is still considering Microsoft’s assertion that the patent holder wrongfully withheld information about the existing technology when filing for the patent.

Acacia, a company that buys patents and licenses them or files infringement suits against companies that do not license, is behind the suit. Acacia bought the patent and formed a company called Computer Acceleration, which filed the action against Microsoft. Another Acacia subsidiary, IP Innovation, sued Red Hat and Novell over a 1991 patent originally granted to Xerox PARC researchers for a GUI software technique.

The plaintiff late in the case sought to add a claim against Windows Vista but the court denied the request.

This is the fourth suit that Acacia or its subsidiary companies have brought against Microsoft. One was settled, another Microsoft won during a summary judgment, and another was just filed on Monday, Microsoft said.

The IDG News Service is a Network World affiliate.