TiVo, the tapeless television recording system, has been criticised for "invading privacy" after its machines started automatically recording the Discovery Channel.

TiVo users found the machines, which record programmes onto a hard-drive, had stored trailers and commercials from Discovery Channel two nights a week.

They had also set themselves to Discovery Channel by default the following mornings.

The BBc got into trouble when TiVos taped the post-watershed Dossa and Joe

But one TiVo user told BBC News Online that the cause was simply a default setting which created a live buffer for users in case they wanted to rewind.

"The fact that it defaults to Discovery channel after you have been watching a recorded programme is completely of no consequence at all," Dr Darren Hudson said.

Last year TiVo was criticised when recorders automatically recorded an episode of the Caroline Aherne comedy Dossa and Joe.

Users of the service in the US have said the action is an invasion of privacy.

But Discovery have denied there is anything suspicious about the recordings.

It says TiVo automatically tapes "dead time" when it is not being used.

Hundreds of complaints

Discovery says the network just happens to be the channel the TiVo system chooses.

The TiVo recorders allow users to record 40 hours of television on to a hard drive instead of tapes, and they can also pause live television.

The machines can make recording suggestions or automatically record a viewer's favourite programmes.

Hundreds of British TiVo users complained last year when their machines had taped an episode of Dossa and Joe after the BBC sent out a recommendation.

There was also criticism over the fact the BBC had used a post-watershed programme.

The BBC said the episode had not taken up any space on users' hard-discs, but there were complaints the programme was impossible to delete.