If the Start/Finish is not set beforehand, you could auto-set it by setting it at the point where the GPS trace hits itself again. Basically as they enter the track, they will do a full lap and when they come back around they will hit their GPS trace where they first entered the track. Obviously this point will not be the real Start/Finish of the track as it will most likely be just after Pit Out, but it is better than not getting any lap numbers or lap times.
-Scott
Suggestion how to auto-create Start/Finish if not entered
Alternatly (or additionally), I would love to see a feature in the software where you could designate start / finish / split time points after the data has been collected and then have the software reprocess the data to add lap time / split time info, perhaps saving to a new CSV so as not to affect the original data. It is not always practical to figure out the GSP coordinates of all these points before hand.