The European Commission fined Microsoft $375.4 million for failure to comply with antitrust rulings.
The European Union had previously fined Microsoft approximately $634.7 million in 2004 for taking advantage of its monopolistic position in the market. The amount of the fine comes from the number of days the EU waited for Microsoft to comply.
The EU had previously told Microsoft to open up its code as well as open up its Windows operating system to competitors.
Competition Commissioner Neelie Kroes told reporters that "Microsoft has still not put an end to its illegal conduct. I have no alternative but to levy penalty payments for this continued noncompliance."
If Microsoft still does not comply by July 31st of 2006, it will be fined approximately $3.83 million per day.

This news article was written on July 12, 2006, quoting Yahoo.