The European Commission's antitrust division in 2009 ordered Microsoft to extend browser choices to customers who had been buying operating systems that had been providing access exclusively to Microsoft's Internet Explorer.
In 2009, Microsoft signed the deal agreeing to offer more browser options on future operating systems. CNet reported.
"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," said the European Union's antitrust commissioner Joaquin Almunia.
"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," he said.
Microsoft said its failure to comply with the directive for more than a year was a "technical oversight,."
On Wednesday, a company spokesperson in Brussels said the software giant takes "full responsibility for the technical error."
"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," the spokesperson said.
CNet said Microsoft failed to extend browser choices on new Windows 7 operating systems from February 2011 through July 2012. Microsoft said 28 million users were affected by the oversight, a figure the European Commission allowed was closer to 15 million.
The number is critical, because the fine could have gone as high as 10 percent of Microsoft's global sales, which would amounted to a fine of $7.4 billion.
Analysts did not expect the commission would levy a fine of that size, but they expected a high enough number to show other companies that it meant business when it came to antitrust issues.