Recently it was it formed by the European Commission that European competition law has been violated by Microsoft by including Internet Explorer with Windows.
It was also informed by the Commission that since Windows includes Microsoft's own browser; the other browsers are prevented from competing with IE.
It should also be noted here that under the European law, IE's inclusion is not made by the remedies put in place under the US government's landmark 2002 antitrust settlement with Windows lawful.
Microsoft had agreed to separate IE from Windows and permit users to de-select IE as their chosen browser under that ruling.