Microsoft Corp.'s MSN search engine stopped working for about four hours Thursday morning, and the company couldn't immediately say what caused the problem.
The search engine stopped working around 8:30 a.m. PDT Thursday and was being restored around 12:15 p.m. PDT.
(MSN Search is the primary search engine for MSNBC.com, and MSNBC.com content is distributed by MSN. MSNBC itself is a Microsoft - NBC joint venture.)
During the outage, users who tried to find Web pages were told the service was unavailable and that, "Our team is working to restore service as quickly as possible."
Microsoft spokesman Justin Osmer said in an e-mailed statement that the company was still trying to diagnose the problem.
Microsoft's MSN Search is the third-most-popular search provider in the United States, according to Nielsen/NetRatings, behind market leaders Google Inc. and Yahoo Inc. Nielsen/NetRatings said MSN provided 10.7 percent of all U.S. search results in February, compared with 48.5 percent for Google and 22.5 percent for Yahoo.