Microsoft last week began providing European consumers a "browser ballot screen" for Windows 8, a move that may be just the first of several steps the company will take to head off a new antitrust investigation.

According to the Reuters news service, Microsoft has assured European Union (EU) antitrust regulators that they "will comply immediately" with issues Brussels officials have raised about Internet Explorer (IE), Windows 8 and its offshoot for tablets, Windows RT.

At an economic conference in Italy on Saturday, European Commissioner Joaquin Almunia said Microsoft's chief executive had pledged to address the EU's concerns about the company's browser practices.

"In my personal talks with Microsoft CEO Steve Ballmer, he has given me assurances that they will comply immediately regardless of the conclusion of the antitrust probe," Almunia told reporters.

In July, the European Commission's antitrust agency, which is led by Almunia, launched a probe when it discovered that Microsoft had failed to abide by a 2009 agreement requiring it to offer consumers a choice of browsers other than IE.

Almost immediately, Microsoft apologized, claiming that the failure to offer the browser choice screen to Windows 7 users for nearly a year-and-a-half was a "technical error." Microsoft faces fines that could run into the billions of dollars for the oversight.

Days later, the Commission confirmed that it had widened the investigation to account for several other complaints, including that Microsoft was withholding Windows 8 and Windows RT APIs (application programming interfaces) from rival browser makers.

If, as Almunia implied, Microsoft will deal with all of the EU's concerns, it would have to tackle the expanded list of investigated topics, among them whether Microsoft must offer a browser ballot on Windows RT and open up access to all APIs in Windows RT.

Both Google and Mozilla are working on versions of their browsers that will run in the so-called "Modern" user interface (UI) featured on Windows RT and Windows 8.

Mozilla has been the most vocal about Microsoft's refusal to give outside developers access to the same Windows RT APIs that Microsoft allows its programmers to call for IE10.

Without those APIs, Mozilla has argued, it cannot build a Windows RT version of Firefox that's competitive with IE10. Google has decided to move forward on a "Modern" Chrome app even with Microsoft's restrictions, perhaps thinking that regulators would eventually step in and force Microsoft's hand.

Almunia's office has declined to identify the source of the complaints that led to the expanded investigation.

The Windows 8 browser ballot issue was apparently not in dispute, however. Although Microsoft had declined to comment when asked in May if it believed it must offer a ballot for Windows 8, the new operating system was never mentioned by the Commission in its July announcement or subsequent comments about a broader probe.

On Sept. 4 Microsoft quietly began pushing a ballot screen through its Windows Update service to Europeans running Windows 8 RTM, the final code released to many enterprises and some users in the weeks before. Windows 8 RTM, or "release to manufacturing," shipped without the browser ballot.

Microsoft also updated a support document related to the browser ballot to include references to Windows 8, and to describe the changes that take place if a user selects a browser other than IE. The support document makes no mention of Windows RT.

Microsoft declined comment on the Reuters report, or to disclose what other steps the company may have pledged to take. The European Commission was not available Sunday.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, or subscribe to Gregg's RSS feed . His e-mail address is gkeizer@ix.netcom.com.