Britain's Elise Christie was penalised for the second time at the Sochi Olympics and forced out of the short track 1500m in the qualifying heats.
She finished first but was deemed not to have crossed the official line marked in the ice. She was wide by 1cm.
It came two days after she was penalised in the 500m final, in which she had finished second.
"I didn't expect it," Christie said. "When my name didn't come up on the screen, I was just really confused."
Christie's main event is the 1000m, with the heats on Tuesday and the final on Friday.
The 23-year-old said she had been the victim of cyber bullying since the incident on Thursday and a decision was taken to delete her Twitter account.
An emotional Christie told BBC Sport: "I have found it hard, but it is not always about medals. I have to keep pushing through."
In the final straight at the Iceberg on the Olympic Park, the Scot moved inside and, with a burst of speed, passed Arianna Fontana, the Italian she had collided with in the 500m race.
The judges were reviewing the photo finish and that is when they spotted the infringement.
Christie was slightly wide of the official line and Team GB decided not to appeal against the decision having looked at the race footage.
Her coach, Nicky Gooch, who won Britain's only short track Olympic medal, in the 500m in 1994, said: "To the letter of the law it's probably right but she's clearly qualified through that race but the rules say you can't be inside the line."
Performance director Stuart Horsepool said the sport was unpredictable but the team were hoping their luck would change.
"We are talking about the smallest margin ever. There is nothing we can do. She was trying to win the race, she was lunging for the line," he said.
"She was making sure she was safe and she went what we are talking millimetres. These things happen in sport and there is no accounting for it.
"Luck doesn't even come into it. We have to pick ourselves up and come back on Tuesday and hopefully we can have good luck instead of all this horrendous back luck."
Christie's main event is the 1000m and she is considered a strong medal contender after becoming the first British woman to win a medal at the World Championships and she was the overall World Cup winner in 2013.
"I'm looking forward to getting back out there for the 1000m but it's been a hard few days and I'm struggling to bounce back. I'm just going to try my best," she added.
Defending Olympic champion Yang Zhou, of China, won gold with Korean Suk Hee Shim taking silver and Arianna Fontana, of Italy, bronze.