Microsoft has restored its MSN Web sites and services that were inaccessible on the weekend and left many users unable to access game, Web-based e-mail, chat and search features, among others.

The outage also brought down for a while MSNBC.com and Newsweek.com, which has a hosting arrangement with the Microsoft-NBC news site.

The outage is one in a series of recent glitches affecting MSN Web sites or Passport online authentication. Users could not access Microsoft's popular Game Zone Web site, nor could they log in to popular MSN chat rooms. Some Hotmail users also found they could not access the Passport log-in page for accessing the Web site. The outage also affected Internet Explorer 6 users, who discovered they could not search the Web using the default setting. IE 6, which is integrated into Windows XP, uses MSN for Web searches.

"This also affected people wishing to sign-out of their Passports on the Zone.msn.com site, causing a potential security issue for that segment of their Passport access," said Shane Johnson, US a network/messaging consultant.

Users of services such as bCentral, Game Zone and Hotmail, all Microsoft services requiring Passport authentication, typically need to log out of the service to avoid exposure to a possible security problem. This removes a cookie that if pilfered by a Web site or other program that could allow a hacker to take control of the account. So not being able to log out could be as much a problem as not being able to log in.

CNET News.com started receiving user complaints and later confirmed through testing that some kind of failure had occurred with a number of MSN Web sites or services. Most services appeared to have been restored early Sunday afternoon.

Johnson was one of those users alerting CNET News.com to the problem. He concluded that Microsoft had a problem with one of its primary backbone routers.

Microsoft could not be reached for comment about the problems.

Microsoft's .Net Messenger service appeared unaffected by the outage as well as the main MSN and Microsoft Web sites.

Sunday's outage follows a string of gaffes or security glitches that continue to call Microsoft's .Net Web services strategy into question.

In court last week, testifying as part of Microsoft's antitrust trial, Jim Allchin, the senior vice president responsible for Windows, described .Net My Services as being "in a little bit of disarray."

In April, a server glitch locked many Hotmail users out of their accounts. In January, a glitch with Passport authentication blocked some users from accessing Microsoft's game site. This followed a more serious December crisis, when Microsoft's switching users over to Passport authentication prevented some users from logging onto the Web site.

On Wednesday, Microsoft warned of a critical security hole in MSN Messenger's chat feature. In February, a fast-spreading worm exploited a glitch in MSN Messenger, while another problem prevented some Windows Messenger and MSN Messenger users from staying connected to the Internet. A summer 2001 outage kept about 10 million Messenger users offline for about a week.

Instant messaging is an important component of Microsoft's .Net My Services strategy, the company's consumer Web services offering that is under construction. Microsoft plans to use Windows Messenger, which is integrated into Windows XP, and MSN Messenger as a back haul for the company and third-party service providers to communicate with customers. The first service, .Net Alerts, delivers stock quotes, traffic reports and other information through Microsoft's instant messenger.

Other security problems continue, despite Microsoft Chairman Bill Gates' call that the company put more emphasis on making software secure than adding new features.

In March, Microsoft issued a pair of patches for Internet Explorer security holes. February and April security holes potentially opened Office for the Mac to hackers. Also in April, Microsoft issued fixes for about 10 security holes affecting three versions of Internet Information Server.

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