The media regulator Ofcom has begun an investigation into claims that TV footage promoting the London 2012 Olympics has triggered epileptic seizures.
The new Olympics logo was launched in a blaze of publicity
BBC News media correspondent Torin Douglas reports on the subsequent row that has broken out.
The row over the look of the Olympic logo is bad enough for the Games organisers.
The claim that animated footage promoting the Games has caused epileptic seizures is potentially more serious, and a blame game has began to identify who is at fault.
And with the London mayor Ken Livingstone saying the designers of the much-criticised logo should not be paid, there could be financial consequences.
According to the charity Epilepsy Action, at least 18 people have reported having epileptic seizures after watching the flashing, graffiti-like TV footage promoting the Olympics - in particular, a sequence of a figure diving into a swimming pool.
It's widely known that flashing images and other patterns can cause problems for viewers who have photosensitive epilepsy. Broadcasters often give warnings before sequences showing flash photography.
Ofcom has strict guidelines on the issue and has now begun an investigation after complaints from viewers.
Simon Wigglesworth of Epilepsy Action said the potential effects should have been identified earlier.
"There is machinery available that allows people - broadcasters, movie makers, advertisers and so on - to check the images that they're producing, prior to broadcasting, to identify whether it is likely to cause a problem with photosensitive epilepsy.
"They really should have checked first."
In fact, warnings about flashing images were given before the footage was first shown at the logo's launch on Monday, when broadcasters were present.
It's not clear that these were passed on to viewers at the time, or in subsequent news coverage.
The London Organising Committee for the Olympic Games (LOCOG) has removed the footage from its website but, so far, it's the broadcasts that are thought to have caused the main problems.
The BBC and other broadcasters have advised programme-makers to take extra care in how they use the footage and not to use some sequences at all.
LOCOG's spokeswoman says the committee understood that the necessary checks had been made by the company that organised the launch event and it is now carrying out its own investigation.
That company, in turn, used several specialist design and production companies and there could well be legal ramifications as people try to determine who should carry the financial can.
Mayor of London, Ken Livingstone, said the designers of the much-criticised logo should not be paid.
"I remember when I was watching the logo and all those flashing lights I just thought, I assume they've checked this to make sure it doesn't trigger epilepsy in someone," he said.
"If I can think that, what about the firm producing it? You assume when you pay for an advert to be done, they'll do it within the existing legal and health requirements."
But LOCOG said it was the video, not the logo itself, that caused the problems.
Either way, Ofcom's rules make it clear it's the broadcasters that are responsible for what goes out on their screens.
It's now investigating exactly where and when the footage was shown, and which broadcasts may have triggered an adverse reaction in photosensitive viewers.