In a preliminary ruling, the European Commission has found that Microsoft (MSFT) failed to comply with an order that requires it to offer a choice of web browsers to Windows PC buyers. The software giant previously admitted to a “technical error” in its Windows 7 operating system that prevented a browser choice screen from being displayed. If found guilty, Microsoft could face a fine of up to 10% of its global turnover.

“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,” Microsoft said in a statement. “We sincerely apologize for this mistake and will continue to cooperate fully with the Commission.”

EU Competition Commissioner Joaquin Almunia told reporters on Tuesday that there are “no grounds to pursue an investigation” into the browser options in Windows 8 and Windows RT, Reuters reported. The Redmond, Washington-based company has four weeks to respond to the commission’s charges.