Maybe your data is in feet or surveyfeet and not in meters. It should be meters. Check that first, and convert it to meters, command example here:
http://www.attackpoint.org/discussionthread.jsp/me...
I think I have experimented with Pennsylvania data some time ago, but I can't remember was there any issues, like having to re-classify the data or something.
But you can drop me a link to one of the tiles you are working with and I'll try to take a look.