High traffic disrupted Wal-Mart Stores Inc.’s Web site for much of Friday, one of the year’s busiest shopping days.

The Walt Disney Co. also had problems handling the rush of online activity Friday, while Amazon.com Inc.’s site had brief disruptions a day earlier due to a Thanksgiving Day sale on Microsoft Corp.’s Xbox 360 video game console.

For much of Friday morning, attempts to open Walmart.com resulted in blank pages, delays or other problems. By early afternoon, visitors were simply told to come back later.

Black Friday, the day after the Thanksgiving holiday, marks one of the year’s busiest days for retailers and the official start of the holiday shopping season.

The site appeared to be back to normal mid-afternoon Friday, after frustrating countless potential shoppers.