are the displacements reasonable?
are you getting a large displacement warning when running the solution?
i haven't downloaded your files but if you look at many of the discussions where the results are far too high, often soft springs or the large displacement error have cropped up and the solution needs to be looked at carefully before taking them for what is on the screen
also there are locations of high stress like singularities, if you are just looking at the max plot, you might be gettting caught. look at the displacements, look at the forces being balanced. if those are true, then evaluate the stresses and where they are.
only you can tell us if the stresses are true based on your experience and back of the envelope calcs you're backing your FE up with
Impact is a tricky simulation, as there is a time based reaction that is difficult to simulate.
Two questions: Are you sure the 6000N load is correct? Or is that load only present in the first milliseconds of impact (prior to major deflection/deformation)?
Second question: What are the loads acting on? A load of 1N placed on a theoretical "point" would cause infinate stress....
 and now I realize that Jared already basically pointed out both points above. duh.