Old game I know but just though I would inform those unaware just how glitchy this game is. I recently played through it and game across a number of glitches which caused some issues, mostly just graphics or weird one off physics glitches however I did find a gamebreaker glitch which caused me to have to restart the game from the begining (was has half way through...)
On the level south mexico, there is a point when you are driving down the road you can go left continuing on the path or right to a building. if you happen to go left, this will cause a series of ramps to be lowered which are meant to be raised. Without these ramp up you cannot progress in the game. The cause of this being you have to go in to the building to change the chapter. I would advice that you save multiple times during the south mexico chapter encase you get this glitch.