Microsoft has been fined half a billion pounds by European regulators for breaking an agreement to let users pick a browser of their choice when loading up Windows.
Back in 2009 Microsoft agreed to offer European consumers a choice of up to 12 browsers in Windows 7.
The company had agreed to the pledge in order to settle the antitrust investigation, and stave off a penalty of up to 10% of its global revenue.
But because of what Microsoft called "a technical error" that choice was apparently removed with the release of Windows 7 Service Pack 1.
At the time Microsoft said it had "taken steps to strengthen our internal procedures to help ensure something like this cannot happen again". It also restored the choice screen.
But that was not enough to halt a new investigation by the European Commission in July. Last October it announced that Microsoft had indeed broken its agreement.
The EC claims 15 million Windows users in the EU did not see the choice screen between May 2011 and July 2012.
In a press statement the EC announced it had imposed 561 million euro fine - about £484 million.
"I hope this will make companies think twice before they ever thinking of breaching their international obligations," said Joaquin Almunia, vice-president of the European Commission.
"In 2009, we closed our investigation about a suspected abuse of dominant position by Microsoft due to the tying of Internet Explorer to Windows by accepting commitments offered by the company. Legally binding commitments reached in antitrust decisions play a very important role in our enforcement policy because they allow for rapid solutions to competition problems. Of course, such decisions require strict compliance. A failure to comply is a very serious infringement that must be sanctioned accordingly."
A spokesperson for Microsoft said:
“We take full responsibility for the technical error that caused this problem and have apologized for it. We provided the Commission with a complete and candid assessment of the situation, and we have taken steps to strengthen our software development and other processes to help avoid this mistake – or anything similar – in the future."