Null vec3d in vec3d normalize.
Trace out of vecmat.cpp and find offending code.

<no module>! KiFastSystemCallRet
<no module>! WaitForSingleObject + 18 bytes
<no module>! SCP_DumpStack + 354 bytes
<no module>! Warning + 430 bytes
<no module>! vm_vec_copy_normalize + 80 bytes
<no module>! vm_vec_normalize + 43 bytes
<no module>! radar_plot_object_orb + 709 bytes
<no module>! ship_process_post + 712 bytes
<no module>! obj_move_all_post + 553 bytes
<no module>! obj_move_all + 355 bytes
<no module>! game_simulation_frame + 1075 bytes
<no module>! game_frame + 491 bytes
<no module>! game_do_frame + 237 bytes
<no module>! game_do_state + 379 bytes
<no module>! gameseq_process_events + 237 bytes
<no module>! game_main + 782 bytes
<no module>! WinMain + 330 bytes
<no module>! __tmainCRTStartup + 358 bytes
<no module>! WinMainCRTStartup + 15 bytes
<no module>! RegisterWaitForInputIdle + 73 bytes