Just had this happen when I watched the LFSEA_SCS08_Rd1_R2.mpr Replay posted in the Skin section (all 30 cars wear 2048 skins)

I windowed LFS, where it ran at only with around 2 Frames, switched back to fullscreen and this picture came out. I closed LFS via ALT-F4 to prevent a system crash.

Edit: I just tried to restart in the Y14 testpatch version, but the same artefacts occured (I watched the replay in normal Y, I have to seperate installs)

Blackwood GP heh?? IDK I had the same problem, but with LFS viewer. Then I changed the resolution to lower, and everything was fine.
I would recommend downloading a fresh LFS and update to the latest test patch. I don't use any addons, such as high res packs, and so on... Check if you get the same problem or not.

i get that sometimes, but i can`t reproduce it.

Also happened in single player, without too much AI`s.
The only thing i could do, without disconnecting (if online) was to Shift+O quickly, hit the "Screen" Menu (2nd from top), and check another resolution. Or changing same resolution from 32 bits to 16, and back.. works like a charm.. for me.
PS:Valid for patch X and Y.. more frecquent on Y tho.. 5-6 times by now - only once in X (iirc).