Do I have the right to question things with my boss?

Hi, I want to bring something to my boss's attention as it may put the business in jeopardy. He is aware of it and admits the problem but he needs to be constantly reminded of this as he is not really strong willed. He wont fire me but I feel terrible telling him how to do his job. I usually have a speech prepared but then he comes and says hi, I dont have the guts to say it to his and cant say it to him especially when hes being nice. Its actually quite funny.