Amazon, Wal-mart and Gap were all affected by a hacker attack on the west-coast internet traffic.

Folks attempting last-minute shopping at Amazon, Wal-Mart, the Gap, and the travel site Expedia were ankled by outages and slow web browsing as a result of the DDoS attack. Other websites impacted include Salesforce.com and Linden Labs (maker of the game Second Life)….

The websites were only down for about an hour — but needless to say at a very inopportune time for some. Neustar said that it first detected the trouble around 4:45 p.m. Pacific Time (12:45 AM Thursday, GMT).

Two days after Christmas, the Yahoo! Stores too went down for a few hours. I reported that here.

But all of that is minor compared to the Yahoo! Store outage on the cyber monday of 2007.

45,000 small businesses that host their web-stores on Yahoo! Stores lost 4 hours of sales on the biggest e-commerce volume day of the year (Monday, Nov 26, 2007)

Merchants I have spoken to say they noticed a problem with transaction completion beginning at 6 am PST today. At 8:31am, Yahoo posted the first message on its Merchant Solutions website: “Some merchants are reporting that shoppers are receiving an error message indicating ‘system unavailable’ during the checkout process. We are aware of this issue and are currently investigating. More information will be provided as it becomes available.”

“It’s very frustrating. It starts with your investment in marketing the month prior to the holiday shopping season as well as how you schedule your inventory position.”