Can't load any track

[CrystalH]

Ok, I've debugged today a bit further. This is extremely strange and I don't know what's wrong.
I've put a breakpoint in bool MODEL_JOE03::Load,
it is hit when entering track menu, the rotating car is loaded, and is there,
but when I press practice game it does not get hit at all (it should several times right?).

I've done also following, in game.cpp:
bool GAME::NewGame(bool playreplay, bool addopponents, int num_laps)
it fails here:
if (!LoadTrack(trackname))
so i commented out the //return false;
then it fails in
if (!LoadCar(carname, carpaint, carcolor, track.GetStart(0).first, track.GetStart(0).second, true, false, carfile))
if I comment out there //return false;
game doesnt crash, starts but it is just black screen with hud times bar, N gear ABS,TCS controls.

Then I went to bool GAME::LoadCar(
and both
if (!car.LoadGraphics(
if (!car.LoadPhysics(
fail, no idea why.

Further, in
bool CAR::LoadPhysics(
the line
if (!dynamics.Load(cfg, size, center, position, rotation, damage, world, error_output)) return false;
fails, going inside the
bool CARDYNAMICS::Load(
it happens just here
error << "No differential declared" << std::endl;
Why ?? LoadClutch,LoadEngine and the 4 methods before it succeed.
if i comment out the return false there it goes few lines but fails in:
bool CARTIRE::Load(
on everything that is supposed to be loaded from it.

Track surfaces were ok and start postions too.
I have put manual arrays filling in code for tire load, but then it failed on some shape_id in FractureBody being null, whatever.

Is something wrong with PTree code ? I don't know what's going on here.
Half of the stuff isn't loaded while the other half is.