Acacia, a company that buys patents and sues other companies, bought U.S. patent 5933639, which was issued in 1999 to Acceleration Software International Corporation, and formed a company called Computer Acceleration Corporation, which then took Microsoft to court. The suit, filed in the U.S. District Court for the Eastern District of Texas, charged Microsoft with infringing on the patent and asked for US$2.50 per copy of Windows XP sold in the U.S. By Microsoft's account, that could have amounted to anywhere between $600 and $900 million. Late in the case, the plaintiff sought to add a claim against Vista but the court denied the request.
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. 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.
News source: PC World