WESTERN DIGITAL - FILE LOCK OUT

Western Digital sells a range of networked hard drives, which allows users to share files across both a local network of home computers and across the net.

But the firm has now blocked remote access to 30 different types of media files, including MP3s and MP4s, to users running its Anywhere Access program.

The company says it has done this as an anti-piracy effort, to prevent people from copying and sharing copyright files.

But the block makes no distinction between files which are user generated, such as home movies, and paid-for, DRM-protected content.

ZUNE - SHARE AND SHARE NOT ALIKE

When Microsoft introduced its Zune media player to rival the iPod it boasted a supposed killer feature - the ability to share songs wirelessly with friends.

Unfortunately, the Zune not only failed to support the Digital Rights Management system Microsoft had pioneered for its partners, it also restricted the sharing of a song to "three plays or three days, whichever comes first".

Users were able to share a song but a friend had a limited number of plays and time, in which to listen to it.

And the restriction applied to any kind of music file - even if it was a track recorded by the user himself.

Strangely, many of the songs offered to Zune users for download from Microsoft's online store could not be shared at all due to "rights restrictions".

Microsoft has now lifted the time restrictions for listening to shared tracks.

NOKIA - FREE MUSIC?

The world's largest mobile phone manufacturer has decided to tackle rampant music piracy by offering tracks for free to its customers.

The Comes With Music service will let owners of its premium handsets download as much music as they like to their phone or PC from the Universal catalogue.

There is no cost to download or a subscription fee. But there is a proviso - if users want to burn the music to a CD to play on a separate player, or in the car, they have to pay out.

GOOGLE - NOW YOU SEE IT, NOW YOU DON'T

Before Google bought YouTube its foray into the world of online video was championed by its own-brand video store. The Google Video store let people buy TV shows such as Star Trek and CSI, which were protected by digital rights management.

Unfortunately, when Google decided to shut down the store in favour of supporting YouTube it left customers who had bought content unable to continue to play their videos.

Google initially offered its customers credit through its own online payment service, called Checkout, but after complaints it changed its mind and offered users a straight refund.

The issue highlighted concerns that digital content bought by consumers that is protected by DRM may not always be accessible if the content producer and/or distributors removes its support for the format.

SONY - THE ROOT OF THE PROBLEM

In 2005 Sony took a new approach to protecting its CDs from copying by including software on the discs which automatically installed on a PC if the disc was played in a computer.

The software was designed to prevent copying but it also left PCs open to potential hacker and virus attacks.

Consumers were not told of the software on the discs and the discs themselves gave no indication of the copy protection software stored on them.

After the problems were highlighted Sony released a tool which would remove the program from users' computers - but it too had security issues.

Sony ultimately recalled the discs with the software installed and after a series of high-profile, class-action lawsuits paid out to consumers who had bought the CDs.

ITUNES - DRM HERE BUT NOT THERE

When Steve Jobs issued his open letter decrying DRM on music many observers felt that the tide was beginning to shift against DRM.

Apple's iTunes store now offers users MP3s of music, without copy restrictions, from the EMI back catalogue.

But Steve Jobs has said the move did not mean an end to DRM on videos it sells via iTunes.

"The music and video markets are not parallel. The video industry does not deliver 90% of its content DRM-free," he said.

CONSOLES - HI-DEF FUTURE?

The Xbox 360 and PlayStation 3 are capable of producing high definition video, up to 1080p, or so-called Full HD resolutions.

If you buy the HD-DVD player add-on for the Xbox 360 you can playback movies in the highest resolution available today, assuming your TV can support it, while PS3s can play Blu-ray movies out of the box.

However, all Xbox 360 consoles sold in the first 18 months from launch, and the first few months in the case of the low-end PS3's availability, do not have a so-called HDMI port. This is a digital interface to output video and audio, which can encrypt the information being sent to the TV to prevent copying.

HDMI is part of a system which allows content producers to protect their material by placing a protection flag on it, called an Image Constraint Token. This means devices that do not have a HDMI port (or DVI port) will not be able to play the content at the fullest resolution.

Potentially, it means many Xbox 360 owners and some early PS3 enthusiasts would not be able to play their legally bought HD-DVD and Blu-ray movies in the best quality, despite the fact Microsoft and Sony are leading supporters of HD technology.

So far, no HD-DVD or Blu-ray titles released have used the protection flag, but the technology is there to be implemented and it could mean millions of console owners would only be able to play their films at a quarter of the potential resolution.

VIRGIN - SHUT OUT

When Virgin launched its digital offering, including a subscription "music club", in 2004 Sir Richard Branson boasted: "With a strong music heritage behind us, as a record label and a retailer, Virgin has a huge advantage, and platform to launch a digital service that will become the ultimate destination to buy, stream, burn and enjoy the best the music world has to offer."

Like many online music stores, it came with DRM designed to prevent copyright theft and to enable users to rent their music.

But when the site shut down in September this year it left members of The Music Club unable to play their songs, because they could no longer renew their monthly fee.

For customers who had paid extra to transfer their music to an MP3 player this was doubly frustrating.