Physicists had detected neutrinos travelling from the CERN laboratory in Geneva to the Gran Sasso laboratory near L'Aquila that appeared to make the trip in about 60 nanoseconds less than light speed.

[...]

According to sources familiar with the experiment, the 60 nanoseconds discrepancy appears to come from a bad connection between a fiber optic cable that connects to the GPS receiver used to correct the timing of the neutrinos' flight and an electronic card in a computer. After tightening the connection and then measuring the time it takes data to travel the length of the fiber, researchers found that the data arrive 60 nanoseconds earlier than assumed. Since this time is subtracted from the overall time of flight, it appears to explain the early arrival of the neutrinos.