I don't think it's a connection issue because it happens the same playing hot lapping.
Now i've reintalled everything and seems to work ok, but i've done it before and after some time it starts to do the same thing.
The "hole" is always on the track, in the usual path.
I hope it doesn't happen again, but it's a really strange thing, because once it starts, the hole is always in the same place, even if i'm playing onlione with more people. The others can see me falling.