Microsoft blamed its own technicians for a crucial error that crippled the software giant's connection to the Internet, almost completely blocking access to its major Web sites for nearly 24 hours.

In a statement issued late Wednesday, Microsoft explained that a "router configuration error" had caused requests for access to the company's Web sites to go unanswered.

Routers are critical pieces of the Internet that direct data between a company's network and the Internet.

After replacing the misconfigured files at about 5 p.m. PST Wednesday, traffic to and from the affected Web sites returned to normal, Microsoft spokesman Adam Sohn said.

"This was an operational error and not the result of any issue with Microsoft or third-party products, nor with the security of our networks," he said.

Microsoft's woes began at 6:30 PST Tuesday night and effectively blocked access to some of the Internet's most popular Web sites, including Microsoft.com, MSN.com, WindowsMedia.com, Encarta.com, Carpoint.com and Expedia.com, Sohn said.

Hotmail.com also was largely inaccessible, although the company could not confirm that it was affected by the same problem that severed access to its other sites.

Around 1 p.m. PST Wednesday, some of Microsoft's Web sites had again become accessible from some parts of the country, but access was inconsistent. Four hours later the company declared that full access had been restored.