Amazon.com's Web site experienced problems in North America for more than two hours in the middle of the day Friday because of system issues, the online retailer said.
Shortly after 10 a.m. PDT, the company's retail Web site shut down, giving an error code to anyone visiting it, according to Keynote Systems Inc., a California-based company that measures Web site performance.
"Amazon's systems are very complex and on rare occasions, despite our best efforts, they may experience problems," Amazon spokesman Craig Berman said in a brief e-mail statement. "We work to minimize any disruption and to get the site back as quickly as possible."
As one of the Internet's giants, Amazon attracts massive amounts of traffic and money. Analysts forecast the company will bring in more than $19 billion in revenue this year. Last quarter, the company recorded $2.13 billion in sales in North America.
In April, more than 58 million visitors in the United States went to Amazon.com, according to data from ComScore Inc.
The impact on sales from the blackout was not immediately known.
Shawn White, Keynote's director of external operations, said an error in the configuration of the Web site might have caused the shutdown.
"Even accessing the home page involves complex multistep interactions between the Web browser and a number of back end systems within Amazon," White said. "To do what Amazon does, in providing a highly personalized user-experience with the visual richness users have come to expect, this complexity shouldn't be a surprise. However, the challenge in the IT world is that the more complex something is, the more likely it is to break or be broken."
Berman said the Web services Amazon provides for other companies were not affected, nor were its international sites.
At 10:16 a.m., the Web site began reporting troubles. Five minutes later, it fully went off line. It was back up to 60 percent capability around noon. By 1 p.m., the Web site was at 100 percent, White said.