Amazon Recovers from 2 Hour Blackout Inc was faced with a 2 hour black out on Friday as its Web site went offline in the middle of the day due to system problems, a spokesperson said.

The site prompted an error code to anyone visiting it shortly after 10 a.m. PT, according to Keynote Systems, a California-based company that measures website performance.

“Amazon’s systems are very complex and on rare occasions, despite our best efforts, they may experience problems,” Inc 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.”

Amazon attracts massive amounts of traffic and money. Analysts forecast the company will bring in more than $19 billion in sales this year. Last quarter, the company recorded $2.13 billion in sales in the US.

The site had more than 58 million visitors in the United States in April, according to data from ComScore.

The impact on sales from the two-hour blackout was not immediately known.

While the cause of the outage remained unclear as of Friday afternoon, one expert said it was likely due to the sheer complexity of the site, which tailors content to visitors depending on determining factors such as their geographical location, purchase history and behavior during previous visits.