BRUSSELS: Since the mighty Microsoft was cut down to antitrust size by the European Commission earlier this year, smaller software firms have been emboldened to try their luck in the courts.

Latest challenger is Norwegian company Opera Software, which has filed a suit against the US behemoth over the bundling of its Internet Explorer web browser with the Windows operating system.

Opera, which itself makes browsers for PCs and mobile devices, claims Microsoft is again violating competition laws and has asked the EC to require it either to unbundle Explorer from Windows, offer rival browsers in the default installation, or both.

The software titan ripostes that Windows does not block the use of alternative web browsers, and that consumers and computer manufacturers are free to use any browser with its operating system.

In September, however, Europe's second highest court upheld an EC ruling that Microsoft had transgressed antitrust regulations when it tied its media player to Windows - a decision that has not been further appealed.

Comments Brussels-based lawyer Michael Reynolds: "What has changed is that we now have very clear guidance from the court as to what constitutes bundling and tying.

"I expect that the commission will conduct a thorough examination into this, based on the facts involved in this market."

EC spokesman Jonathan Todd confirmed that competition authorities would review the complaint.

Data sourced from International Herald-Tribune; additional content by WARC staff