As first reported by CNET News.com, some Mozilla and Opera users were enraged Thursday when they could not reach the upgraded MSN site. Instead, they were given the option of downloading a version of Microsoft's Internet Explorer. That same day, Microsoft buckled to protests and said it would open its site to other browsers.
But the uproar spilled into Friday as many Mozilla and Opera users found themselves still locked out.
The episode also raised the ire of Washington-based trade group ProComp, which asked state and federal trustbusters to get involved.
The ongoing antitrust lawsuit against Microsoft, now moving into what should be its final stage, got its start in the mid-1990s because of concerns that the company was using its dominant position in operating system software to gain an unfair market advantage for its Internet Explorer browser.