A Chicago man who bought Microsoft Corp.'s new Xbox 360 has sued the world's largest software maker, saying the new video game console has a design flaw that causes it to overheat and freeze up. The proposed class action claims that in Microsoft's bid to gain share in the $25 billion global video game market, the company was so intent on releasing the Xbox 360 before competing next-generation machines from Sony Corp. and Nintendo Co Ltd. that it sold a "defectively designed" product.

Robert Byers, who brought the suit, said the power supply and central processing unit in the Xbox 360 overheat, affecting heat-sensitive chips and causing the console to lock up.

Microsoft spokeswoman Molly O'Donnell on Monday said the company does not comment on pending litigation.

Complaints about the problem surfaced quickly on gaming enthusiast Web sites after the Xbox 360 debuted on November 22.

Console owners reported that some systems had crashed during regular use as well as during online game play using the Xbox Live service. Problems included screens going black and the appearance of a variety of error messages.

At the time O'Donnell had said: "We have received a few isolated reports of consoles not working as expected."

She declined to say how many reports Microsoft had received and said that calls reporting the issue to the company represented a "very, very small fraction" of units sold.

The lawsuit, filed on Friday in federal court in Illinois, seeks unspecified damages and litigation-related expenses, as well as the replacement or recall of Xbox 360 game consoles.