In the filing, Microsoft states that the EU is thinking about forcing Microsoft and OEMs to offer customers a choice of browser when they're setting up their computers, which would mean that they have to ship several browsers on machines. Microsoft explains in the filing:
Non-compliance could lead to a significant fine based on the number of Windows computer sold, Microsoft said. In addition, the company also stated that the EU is still investigating Microsoft Office, and any possible problems in that area.
While I personally applaud any investigation into possible unlawful competition, I do believe that forcing OEMs to offer customers a choice of browsers is a bit odd, as this would create unfair competition by itself: sure, you can include Firefox, IE, Opera, Safari, and Chrome in this choice - but what about other browsers? Where do you draw the line? How would newcomers enter such a market?
I think the most reasonable thing to demand from Microsoft is that Internet Explorer can be fully removed from Windows, and replaced by another browser. Shipping an operating system without a browser is ridiculous; forcing customers to choose between an arbitrary set of browses even more so.