The software giant claimed it was repairing a technical glitch that prevented users of Opera, Mozilla, and other browsers from accessing MSN.com.
However, Opera CEO Jon von Tetzchner contends that this was not a technical glitch, but a deliberate Microsoft strategy to handicap his company.
Von Tetzchner claimed in a telephone interview that MSN.com blocked access to users whose browsers identified themselves with the string of characters "Opera,". By simply changing one letter, sending the string "Opra," for example, they could gain access. That suggests that Microsoft had put Opera on a "black list," he said.
While he acknowledged that Microsoft has since corrected the situation, he pointed out that parts of MSN.com - such as the Carpoint.com automotive site - were still inaccessible to Opera users Thursday.
He firmly rejected Microsoft's assertion that Opera and Mozilla do not adequately support the World Wide Web Consortium (W3C) standard XHTML (Extensible Hypertext Markup Language). Once Opera users are granted access to MSN.com, XHTML pages render "just fine," he claimed.
He accused Microsoft of using strong-arm tactics to disadvantage his company, suggesting Redmond has designs on one of Opera's chief markets.
"We have been making significant deals in the Internet device market, and Bill Gates has been on record saying the Internet device market will dwarf the PC market in a few years. Microsoft wants that market, so in essence they're trying to use their power in the PC market to gain dominance there," he said.
In related news, Hotmail users who fail to sign into their accounts at least once every 30 days will find their accounts deactivated, Microsoft warns. Such accounts previously expired after 45 days.