Microsoft has trumpeted its Xbox Live online gaming and download service as its key weapon in the battle for console supremacy with Sony and Nintendo.

"To celebrate its first birthday... Xbox 360 becomes the first and only gaming console to provide HD and standard-definition TV shows and movies direct to you," states the Xbox website.

The announcement of a video download service was made earlier this month, with more than 750 hours of TV and films promised - both in standard and high definition quality.

Gamers can buy TV programmes but the movies are rented and are automatically deleted from the console's hard drive after a fixed period.

"We've made progress over the past 24 hours, and the team is dedicated to fixing the issues and continues to work as fast as they can around the clock to get the service running as seamlessly as you have come to expect," wrote Mr Hryb, who is Xbox Live's director of programming, on his Major Nelson Xbox blog.

Xbox owners experiencing problems have been told to contact customer support on 1-800-4MYXBOX.

The problems reflect the difficulty companies - even those of the size of Microsoft - are having in getting video into the online age.

Video content in high definition results in very large file sizes - which can put a strain on servers when delivering content to thousands of people at the same time.

Some gamers are reporting that they are receiving different programmes from the ones they have paid for, while others have complained downloads are taking hours to arrive.

A standard definition TV programme costs $2 (£1.03), while a high definition version costs $3 (£1.55). Rental costs for films are $4 (£2.06) in standard definition and $6 (£3.10) in high definition.