In looking through a new data set, I came across two instances where a stimulus was presented, a 10 was recorded as the response from the DirectRT button box (in the input file, time was rt:1,9). These two trials also had no time value recorded in the output, but a negative time value was recorded in the Log file (-518547 in one case, -677371 in the other). It only happened on two out of more than 11,000 trials so it's not a major catastrophe...but in one case it ended the experiment early (the third block of trials did not appear for the participant). In any event, I'd like to understand what is going on here.

Some additional information - the errors occurred with different participants, collected on different computers, on different days/times, and with different stimuli.

Have others had this happen? Does anybody know the reason?

Thanks...
David