A runtime warning message

Hi G4ers:
Recently I was doing an experiment. Used an external OBJ file for the brain model import, then detect the energy deposition and particle location in the brainstem region. But when I run the program in multi-threaded mode, I get this warning message:
G4WT5 >
-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
Track stuck, not moving for 10 steps.
Current phys volume: ‘World’

  • at position : (14.28853007145441,15.25205063979755,-515.044095475125)
    in direction: (0.01745177309326686,0.02416067588098988,-0.999555749999406)
    (local position: (14.28853007145441,15.25205063979755,-515.044095475125))
    (local direction: (0.01745177309326686,0.02416067588098988,-0.999555749999406)).
    Previous phys volume: ‘physicaltest’

Likely geometry overlap - else navigation problem !
*** Trying to get unstuck using a push - expanding step to 1e-07 (mm) … Potential overlap in geometry !
I don’t know what’s wrong, does this warning affect the accuracy of the experimental data, or is there something wrong with my experimental program.
In addition, I would like to ask the experts what kind of method you use to build the brain model and how the brain material is defined.
Here first thank you for your answers, for a newbie your advice is very valuable to me.