The problem began Sunday evening and caused scores of complaints to hit Internet message boards Monday--most from people who say they were unable to log onto PayPal's site.
X.com-owned PayPal is a service that allows its 4.5 million customers to send money via email. It is particularly popular for those who buy or sell goods at online auctions. Complaints quickly popped up on the message boards of online auction giant eBay: "I have not been able to access my money all morning," one person wrote. "I need my money!"
PayPal spokesman Vince Sollitto said the holiday traffic caused the initial stall. Once Palo Alto, Calif.-based PayPal saw the site was bogged down, it began to bolster its systems, but the upgrade took longer than expected.
Technicians had the site running properly by Tuesday morning, he said.
Other Web sites struggled through the holiday traffic as well. Online retail stores such as BlueLight.com, EddieBauer.com and Gap.com last week saw their sites take double the time to download compared with the first week of November, according to traffic-tracking company Keynote Systems.
Other sites suffered total blackouts last week, but most denied heavy traffic was the cause.
Amazon.com, which had more than 1 million visitors on its site Friday, according to traffic-tracking company Nielsen/NetRatings, went dark for 30 minutes. BestBuy.com, the Internet unit of electronics retailer Best Buy, also suffered sporadic outages over the weekend. Online grocer Webvan also saw some sporadic outages during the week before the Thanksgiving holiday in the United States.