Jessica Ennis was denied a personal best in the 100m hurdles at the Great CityGames in Manchester because only nine of the necessary 10 barriers were laid out by the organisers.
The Team GB heptathlete clocked 12.75 seconds but her time does not stand.
Ennis said: "I am so annoyed. I still had a good competitive race, but I've just not got the result I wanted."
Dwain Chambers finished second in the 150m, his first race since learning he can compete at London 2012.
Ennis was delighted with her performance, but said she "can't believe" the "massive, massive mess-up" with the number of hurdles.
"I knew it was going to be a tough race against some quality athletes and hopefully I can keep it going for a few more months."
A spokesman for the organisers, Nova International, said: "There has been a technical error and there were nine sets of hurdles out on the course instead of 10.
"We'll conduct a thorough investigation and find out what happened and why and by whom.
"It's a very unfortunate mistake, we're very unhappy about it."
Chambers started strongly but American 200m specialist Wallace Spearman powered past the Briton in the final third of the race to secure victory by four tenths of a second.
"They are all challenges and I need to keep my head focused on the races I've got coming up," said Chambers.
The sprinter, who recently found out that he was eligible to seek a place in Team GB at London 2012 after the British Olympic Association lost its attempt to maintain lifetime bans for drugs offenders, added: "I need to stay injury-free and make sure I make the team."
Andy Turner made a decent start to the 110m hurdles but took the sixth and seventh barriers off-balance, costing him vital momentum. It allowed Ryan Brathwaite from Barbados the opportunity to win, with American David Payne in second and Turner fourth.
The Briton recovered in the 200m hurdles, though, and clinched victory by two tenths of a second despite knocking over the third barrier.
"I think I tried too hard in the first race," said Turner. "Myself and David Payne were punching each other all the way.
"I feel fine and my training is going well. I just need to do it in a race."
Germany's Verana Sailergot off to a powerful start in the women's 100m but Lashaunte Moore of the United States found an extra gear over the final 20m to clinch victory with 38-year-old Briton Joice Maduaka fourth.
Moore then showed her class to win the 150m with some comfort, ahead of Britain's Montell Douglas in a creditable second.
The men's 100m was a close-run affair but Britain's Christian Malcolm won it by one hundredth of a second from France's Jimmy Vicaut with home runner Mark Lewis-Francis just three hundredths of a second back in third.
Jaysuma Ndure took the honours in the men's 200m, narrowly beating Team GB hopeful James Ellington into second.
In the women's 200m, American Sanya Richards-Ross led from start to finish to secure a comfortable victory.
British number one Holly Bleasdale put in a commendable performance in the pole vault but was forced to settle for second behind Germany's Lisa Rysich.