The Windows 7 service pack 1, rolled out between mid-2011 and mid-2012, failed to offer consumers a choice of browser, leading to the EU investigation that resulted in today's fine.
Microsoft said the failure was the result of a technical error and that procedures have since been tightened.
In what was seen as an acknowledgement of the severity of the mistake, the board cut the bonus of chief executive Steve Ballmer last year, according to company's annual reports.
More top news
Mild in the south but colder in the north tonight and turning frosty and icy - before rain moves in.
The flame-haired prince told youngsters in Africa he did not enjoy Eton and is "much cooler" than his older brother.
Some Scottish social media users were left confused when Facebook offered them a Romanian flag, not a Saltire, to mark St Andrew's Day.