Jan. 14 (Bloomberg) -- Microsoft Corp., the world's largest software maker, is facing two new antitrust probes in Europe as regulators opened another front in the dispute three months after resolving a similar fight.

The European Union will investigate whether Microsoft is using its dominance in word processing and spreadsheets to thwart rivals. It also will review whether Microsoft illegally tied an Internet browser to its Windows operating system.

The investigations complicate Microsoft Chief Executive Steve Ballmer's efforts to resolve disputes with the European Commission, the EU's antitrust regulator. In October, Microsoft agreed to license information on its Windows operating system to end three years of wrangling after an EU court upheld a 2004 antitrust ruling by the commission.

``The European Commission definitely has some issues with Microsoft, and I guess they have more ammunition now that an EU court upheld one of their antitrust rulings,'' said Toan Tran, an analyst in Chicago with Morningstar Investment Service who rates Microsoft shares ``hold'' and doesn't own any. ``It gave them a legal precedent to stand on.''

The investigation also will extend to Microsoft products including server-computer software, .Net Internet tools, software for scanning personal computers to find files and Windows Live Internet services.

Microsoft will cooperate fully with the EU and provide all necessary information, the company said in a statement.

Ensure Compliance

``We are committed to ensuring that Microsoft is in full compliance with European law and our obligations as established by the European Court of First Instance in its September 2007 ruling,'' the company said.

Microsoft's efforts to resolve the case last year, which involved claims the company illegally withheld network data from rivals and bundled a media player with its personal-computer operating system, featured Ballmer flying to the Netherlands to have dinner with EU Competition Commissioner Neelie Kroes. In addition to dropping an appeal of the 2004 ruing, the company also paid a 497-million-euro ($739 million) fine in the case.

One of the two probes follows a complaint in February 2006 by a group representing International Business Machines Corp., Sun Microsystems Inc. and eight other companies. The group, the European Committee for Interoperability Systems, claims Microsoft doesn't provide formatting and other information to allow rival products to work Microsoft Office software including Word and Excel.

`Longer-Term' Threat

``If the Europeans force Microsoft to allow unencumbered access to information created in Office by any other program, that is a significant longer-term competitive threat,'' said Brent Williams, an analyst at The Benchmark Co., which has a hold rating on Microsoft shares and doesn't own any.

Microsoft could be fined as much as 10 percent of annual sales for antitrust violations. Jonathan Todd, a commission spokesman, said it's ``difficult'' to put a precise timeframe on how long the probes will last, adding that it depends in part on cooperation from the company.

``This initiation of proceedings does not imply that the commission has proof of an infringement,'' the European Commission, the EU's antitrust authority in Brussels, said in an e-mailed statement today. ``It only signifies that the commission will further investigate the case as a matter of priority.''

Microsoft rose 48 cents to $34.39 in Nasdaq Stock Market trading at 4 p.m. New York time. The stock has risen 10 percent in the past year.

Browser Probe

The second investigation involves a complaint by Opera Software ASA, the Norwegian maker of Web browsers, that Microsoft uses its dominant position to prevent consumers from trying Internet browsers made by competitors.

Microsoft's Internet Explorer was used by 84.7 percent of people who surfed the Internet in June 2007, according to OneStat.com, which tracks Web statistics. That compares to a worldwide market share of 12.7 percent for Mozilla's Firefox browser, 1.8 percent for Apple Inc.'s Safari and 0.6 percent for Opera.

``The Internet browser, this is a market that is, after becoming noncompetitive for a very long time, has, over the last couple of years, become very competitive for Microsoft,'' Williams said. ``In Europe, Microsoft has already lost market share to the Firefox Internet browser.''

Some of the issues in the EU probe were raised in a U.S. antitrust case. A U.S. appeals court rejected a lower court's finding that Microsoft illegally tied its browser to the operating system to thwart competition. The U.S. and Microsoft settled the case in 2001 before a trial court could review the issue.

U.S. court supervision of most of Microsoft's business practices at issue are set to expire Jan. 31 unless a judge grants a request by state antitrust enforcers to extend the order.

To contact the reporter on this story: Matthew Newman in Brussels at Mnewman6@bloomberg.net.

Last Updated: January 14, 2008 16:32 EST