I don't know why bad things happen, at all. This definitely includes why bad things happen to good people, why bad things happen to innocent people, trusting people...
There are lots of responses out there, some of which I admire greatly:
But the fact of the matter remains - I believe in a loving and just God, but unloving and unjust things happen in the world around us all the time. I certainly don't have "the" or even "an" answer.
As Christmas approaches and I listen to tons of holiday music, here is one set of lyrics that really hits the spot for me.