From Microsoft's site

Thu Jan 25 04:20:57 UTC 2001

http://www.microsoft.com/info/siteaccess.htm

"Microsoft Explains Site Access Issues

On Tuesday evening and Wednesday, many Microsoft customers had
difficulty accessing the company's Web sites. The cause has been
determined, and the issue is resolved.

At 6:30 p.m. Tuesday (PST), a Microsoft technician made a configuration
change to the routers on the edge of Microsoft's Domain Name Server
network. The DNS servers are used to connect domain names with numeric
IP addresses (e.g. 207.46.230.219) of the various servers and networks
that make up Microsoft's Web presence.

The mistaken configuration change limited communication between DNS
servers on the Internet and Microsoft's DNS servers. This limited
communication caused many of Microsoft's sites to be unreachable
(although they were actually still operational) to a large number of
customers throughout last night and today.

This was an operational error, and not the result of any issue with
Microsoft or third-party products nor the security of our networks.
Microsoft regrets any inconvenience caused to customers due to this
issue.

At approximately 5 p.m. Wednesday (PST), Microsoft removed the changes
to the router configuration and immediately saw a massive improvement in
the DNS network.

All sites are currently available to customers. Again, Microsoft
apologizes for the inconvenience."