Microsoft could face a $5m (£2.8m) daily fine from the European Union within days unless it reaches a last minute deal over an antitrust dispute.
In March 2004, Brussels found the US software giant guilty of abusing its market dominance and fined the company 497m euros ($655m; £340m).
More importantly, it ordered Microsoft to make a number of changes, such as sharing software codes.
Unless Microsoft complies with this by 1 June, it faces daily fines.
"The deadline is the end of this month and if it's not met then it's the end of the game," European Competition Commissioner Neelie Kroes said last week.
Microsoft is supposed to provide details of how it could bring its practices back in line with EU rules.
In its 2004 ruling, Brussels ordered Microsoft to open up its core software systems to rivals.
This is to enable other software manufacturers to make programs that worked more seamlessly with Microsoft's Windows operating system.
Microsoft was also ordered to provide a version of Windows without its own Windows Media Player, to give rival software makers a chance to compete, and computer makers the option to supply PCs with the media software of their own choosing.
Under EU rules Europe could fine Microsoft up to 5% of its daily global turnover for each day that a decision is not applied to its liking, hence the $5m-a-day figure.
Microsoft has repeatedly said that it has been working hard to reach agreement with the European Union.