When I create a drawing, the lines that should not be visible behind the thin parts are displayed.

This is an accuracy issue. The parts are extremely thin compared to the overall size. I fixed it by changing accuracy from relative to absolute and also the value to the smallest I could set it, which seemed to be .006 absolute for each part and also the assembly. Accuracy is a funny thing and cause unexpected issues.

I don't remember but I think on creo 4, you  may have to enable absolute accuracy using the option enable_absolute_accuracy  yes