Throughout the morning Pacific time, visitors to Amazon's site were sometimes greeted with a "Service Unavailable" message, and sometimes a "We're sorry!" note. While an Amazon representative said the issues had been resolved by afternoon, as of 2 p.m. PST, attempts to access Amazon were met with an unavailability message. The site appreared live again at 2:30, however.
"The site was down intermittently this morning," Amazon spokesman Craig Berman confirmed. He declined to explain the source of the problem, saying, "These are complex systems that have problems some times."
Keynote Systems, which tracks Internet traffic and performance, said Amazon's problems started at 8 a.m. PST time, when outages struck 20 percent of people tapping the site, with the remaining 80 percent experiencing slowdowns of up to a minute. Amazon was back up and running by 9:45, but problems surfaced again at 10:45, according to Keynote.
While the problems largely stopped by 2:40 p.m., Keynote reported sporadic outages affecting a small population of users. Keynote could not determine whether an Internet attack caused the outage, but said the problems only affected Amazon.
"The measurement numbers coming back to norms," said Roopak Patel, senior Internet analyst at Keynote. "The situation hasn't cleared itself completely."
For Amazon, the timing of the slowdown couldn't be worse. With the holiday season in full bloom, the retailer is in the midst of its busiest sales period, and it hassignificant financial growth this quarter. Amazon expects sales to jump by at least 31 percent this quarter to between $2.29 billion and $2.54 billion, and full-year sales to increase 31 percent to between $6.67 billion and $6.9 billion.
In the cutthroat retail industry, any holiday hiccup could mean big trouble. Just ask the world's largest retailer, Wal-Mart. Its stock took a brief nosedive after the company reported lower-than-expected sales during the Thanksgiving weekend, which is considered the busiest shopping time of the year.
Meanwhile, the nation's brick-and-mortar competitors, including Wal-Mart, Best Buy, Target and Home Depot, are trying to complement their in-store sales with online offerings.
Nevertheless, as retailers push sales through their Web sites, it's no wonder online shopping continues to boom. Online spending on the day after Thanksgiving (or Black Friday, a reference to the volume of sales that pushes many retailers into profits), , up 41 percent from $178 million in 2003, according to Web statistician ComScore Networks.
On Thanksgiving day, typically a slow shopping day, online sales totaled $133 million, doubling last year's $67 million, ComScore said. Online shopping visitors accounted for 11.39 percent of all Web visits that day, up from 8.96 percent in 2003, according to online-retail tracker Hitwise.
CNET News.com's Matt Hines contributed to this report.