c++11 std::thread integer division by zero Open GL SOIL

I'm using VS 13 and the thread functionality of c++11 to load in a whole ton of textures to OpenGL using the SOIL library. If I dont use threads ie:

textures_[12] = SOIL_load_OGL_texture(chars[12], SOIL_LOAD_AUTO, SOIL_CREATE_NEW_ID, SOIL_FLAG_MIPMAPS | SOIL_FLAG_NTSC_SAFE_RGB | SOIL_FLAG_COMPRESS_TO_DXT);

it works fine. chars[] is a list of the file names to be loaded in. It works fine in a for loop too ie:

for (int i = start; i < stop;i++)
    textures_[i] = SOIL_load_OGL_texture(chars[i], SOIL_LOAD_AUTO, SOIL_CREATE_NEW_ID, SOIL_FLAG_MIPMAPS | SOIL_FLAG_NTSC_SAFE_RGB | SOIL_FLAG_COMPRESS_TO_DXT);

but when I try to use threads to speed up the process it throws an integer division by zero exception ie:

    for(int i=0;i<13;i++)
{
    threads.push_back(std::thread(&Scene3D::threadfunc, this, i * 491, ((i * 491) + 491)));

}
for (int j = 0; j<13; j++)
{
    threads[j].join();
}

void Scene3D::threadfunc(int start, int stop)
    {
        for (int i = start; i < stop;i++)
            textures_[i] = SOIL_load_OGL_texture(chars[i], SOIL_LOAD_AUTO, SOIL_CREATE_NEW_ID, SOIL_FLAG_MIPMAPS | SOIL_FLAG_NTSC_SAFE_RGB | SOIL_FLAG_COMPRESS_TO_DXT);

    }

Any insight into why this is happening would be greatly appreciated, thanks.