Blocking what I don't want blocked

Greetings!  I have a program that has a section for downloading assets.  OK it's a railroad simulation, Trainz 2009, but it's my after-hours geek therapy as a hard-working nurse.  When I try to download something, it doesn't work.  I have Norton 2010, and when I go to their home page and check on "History" I'm told it's blocked every time.  Therefore, a Norton problem, right?  Today I've been on the phone over an hour waiting for tech support.  I have been all over the Norton page and website, cannot see how to unblock and allow downloads from this source.  Can anyone help me?  I would be most grateful!  -- Best, Michael in Iowa