Wei Qing, General Manager of Consumer Marketing at Microsoft China introduces the company's new Windows 8 software to the media in Shanghai on October 23, 2012. - 

Microsoft could face a hefty fine, after the European Union accused the software giant of failing to comply with an anti-trust agreement.

The complaint centers around an agreement Microsoft signed in 2009 in which the company agreed to offer its customers a choice of web browsers -- not just its own Internet Explorer. With the launch of Windows 7 in February of 2011, Microsoft failed to fully comply with the agreement. While the company admits the failure, it claims it was due to a technical error which it says has now been fixed.

Yet, EU Competition Commissioner Joaquin Almuni, said he does not seem impressed by the explanation: "We have basic principles in our competition rules that if companies enter into commitments they must do what they have committed to do or face the consequences."

Microsoft has already paid out millions of dollars in fines as part of its ongoing fued with EU regulators over anti-trust issues.