GP4Builder problem

Just trying to add the pitlane to my Sebring track (WIP) GP4Builder got stuck with the following message 'Violation d'access a l'adresse 0067DD35 dans le module 'GP4 Builder 2017B.exe'. Lecture de l'adresse 04FFEF74' and I lost the complete work done so far...
What kind of incorrect operation could have been my fault?

It's a system error... there's nothing in here that could help to know what went wrong and why...

Thanks for answering! Meanwhile I reproduced all the lost data and the problem didn't occur a second time... Actually my own fault not to save from time to time...

Hmm, I'm pretty sure I added an auto-save feature... but it's far away in my memory... maybe if you check in the options...