The European Union says it is investigating Microsoft to determine if Windows 8 OS may unfairly handicap browsers from rival companies. EU antitrust regulators are looking into complaints by other software makers that Microsoft is preventing them from installing their browsers in favor of its own Internet Explorer on Windows RT, a version of the Windows 8 operating system designed for tablets and other mobile devices, CNET.com reported Thursday. \"On ARM chips, Microsoft gives IE access special APIs [application programming interfaces] absolutely necessary for building a modern browser that it won\'t give to other browsers so there\'s no way another browser can possibly compete with IE in terms of features or performance,\" Asa Dotzler of Mozilla, which makes the Firefox browser, wrote in a blog. Browsers other than Internet Explorer running on Windows RT can\'t take advantage of the best features of both classic and Metro modes offered by the OS, Mozilla said. The issue has come under scrutiny in the United States, where a Senate committee has said it would examine Mozilla\'s allegations of anti-competitive behavior on the part of Microsoft.