Lego Stunt Rally Track Impassable to computer player

One of the greatest arcade racing games allows one to build a track that can be played with up to 4 players or AI. AI knows how to drive pretty well. However, I managed to construct a track that would never allow the bots' algorithm to succeed!
This track can be downloaded, modified and tested here:
www.mediafire.c...
For hair-splitting lovers: this is not my real voice. It was shifted 2 semitones down as the unchanged version sound awkward. It is... a bit shameful for such an old nobleman like me to have a voice pitch higher than average.