Microsoft admitted to a "technical error" earlier this year after the European Commission announced its plans to investigate how millions of PCs running Windows 7 Service Pack 1 did not display a browser choice screen. The software maker has corrected the error, but if found guilty of breaching its legally binding commitments, Microsoft may be fined up to 10 percent of its total annual turnover.

Microsoft has four weeks to respond to the charges. It issued the following statement in response to the European Commission's investigation:

"We take this matter very seriously and moved quickly to address this problem as soon as we became aware of it. Although this was the result of a technical error, we take responsibility for what happened, and we are strengthening our internal procedures to help ensure something like this cannot happen again. We sincerely apologize for this mistake and will continue to cooperate fully with the Commission."

Update: Reuters reports European Commissioner Joaquin Almunia as saying "there are no grounds to pursue an investigation" into the lack of browser choice in Windows RT. The statement goes against previous reports that the Commission was investigating the issue in response to complaints from Microsoft's competitors.