The Murdochs were accused of sharing Race07 from Atari
Games firms are accusing innocent people of file-sharing as they crack down on pirates, a Which? Computing investigation has claimed.
The magazine was contacted by Gill and Ken Murdoch, from Scotland, who had been accused of sharing the game Race07 by makers Atari.
The couple told Which they had never played a computer game in their lives.
The case was dropped, but Which estimates that hundreds of others are in a similar situation.
The illegal sharing of music, movies and games has become a huge headache for copyright owners.
Some six million people are thought to illegally share files each year, and increasingly firms are getting tough on the pirates.
They are monitoring peer-to-peer sharing networks, such as Gnutella, BitTorrent, and eDonkey, that allow games, music and video to be shared.
Atari has appointed law firm Davenport Lyons to prosecute illegal file-sharers.
It has been acting on behalf of several games firms and partner David Gore thinks there are likely to be many more.
The lawyers in the Atari case turned to anti-piracy firm Logistep, which finds those people illegally sharing files via their IP address - the unique numbers which identify a particular computer.
With this number, rights owners can apply for a court order which obliges internet service providers to hand over the account holder's details.
In the case of the Murdochs, a letter was sent giving them the chance to pay £500 compensation or face a court case.
Gill Murdoch and her husband, aged 54 and 66 respectively, told Which: "We do not have, and have never had, any computer game or sharing software. We did not even know what 'peer to peer' was until we received the letter."
Some sites are undermining efforts to catch pirates
The case has now been dropped by Atari, although the firm is yet to comment on the reasons why.
According to Michael Coyle, an intellectual property solicitor with law firm Lawdit, more and more people are being wrongly identified as file-sharers.
He is pursuing 70 cases of people who claim to be wrongly accused of piracy and has spoken to "hundreds" of others, he told the BBC.
"Some of them are senior citizens who don't know what a game is, let alone the software that allows them to be shared," he said.
Most commonly problems arise when a pirate steals someone else's network connection by "piggybacking" on their unsecured wireless network, he said.
While prosecutors argue that users are legally required to secure their network, Mr Coyle dismisses this.
"There is no section of the Copyright Act which makes you secure your network although it is commonsense to do so," he said.
Mr and Mrs Murdoch do not have a wireless network so their address cannot have been hijacked in this way.
It has not yet been established how their IP address came to be linked to file-sharing.
Some question whether an IP address on its own can be used as evidence.
"The IP address alone doesn't tell you anything. Piracy is only established beyond doubt if the hard-drive is examined," said Mr Coyle.
Firms that facilitate file sharing, such as Pirate Bay, have been undermining efforts by anti-piracy investigators to track down file sharers.
Pirate Bay makes no secret of the fact that it inserts the random IP addresses of users, some of who may not even know what file sharing is, to the list of people downloading files, leading investigators up a virtual garden path.
Despite the problems, rights owners are successfully suing pirates.
In a landmark case in August, games firm Topware Interactive won more than £16,000 following legal action against Londoner Isabella Barwinska who shared a copy of the game Dream Pinball 3D.
It is widely expected that the music industry will follow the lead of the games firms and begin prosecutions next year.
In the UK, claims are brought as civil actions using the Copyright, Design and Patents Act of 1988.