I've had that happen quite a lot and for quite a while now. Particularly on the newer circuits like Mt Panorama and Silverstone.
In fact, in a few of the later Aspec events (the "endurance" races I think), I was doing a lot of the circuit by the track map and memory as it just wouldn't draw the circuit quickly enough.
Even now, the new TT on the Nurburgring with the Lexus, every fifth or sixth restart, it fails to draw most of the beginning of the circuit, so I've usually gone off track at the first or second corner after the start line (it's hard to aim for a corner or avoid a barrier when you can't see it).
It even happened in the VW TT at Madrid. All I could see were a few buildings and the distant skyline of the city where the road should be.
I figured it was just the game being a bit "too much" for the PS3 to handle.
Cheers,
Amateur1.