The war between Microsoft and Google had taken a new turn when Google received complaints on the grounds of anticompetitive behavior and was subject to European Commission’s scrutiny. Microsoft is believed to be behind at least one of the complaints about Google now being reviewed.

In the past, Microsoft had been in question by European Commission regarding its products like Internet Explorer with the Windows operating system. The inquiry was followed by heavy fines and Microsoft's agreement to alter certain business practices. Microsoft agreed, for instance, to ship its Windows 7 operating system in Europe with at least 10 Internet browsers.

Meanwhile, Google under the EU scrutiny has left the investors a little worried. But according to comScore, Google is still dominant in European search market, with 78.9% in January.

And the inquiry at this point is just preliminary.

On the other hand, Google is facing U. S. regulatory scrutiny over its book-digitization project and its proposed purchase of a mobile-ad firm.

Knowing Microsoft's history, regulators may be a little cynical and Google might get benefit of doubt.

The two companies, Microsoft and Google are in cut-throat competition on everything from search, office applications software like email and word processing, mobile and even computer operating systems.