There are two solutions for you problem. Try first:
Check your f1graphic.cfg file (open it with notepad) and search for the line:
1 ; Animation rendering mode. (0 - cheap lighting, 1 - proper lighting, 2 - VS) v2
It must be set on 1
If that doesn't work then i suggest you delete the f1gstate file and the graphic file from your main folder and run the game again, you'll have to recalibrate your sound and graphic settings again and check the pitcrew out, they will be there again
its a bug in gp4 after running it a while !