gfortran compiler error

Hey people I need some help!

So for the past week I've been trying to use this fortran program to deal with this data I have. I'm using a mac on Leopard. I downloaded gfortran .mpkg.zip from macresearch.org and unzipped it. I then tried to install by double-clicking and I got a message "The application Installer quit unexpectedly." This happens whenever I try to install something, so I use pacifist (application that can open pkg/mpkg's and install them just like installer). I clicked install to default locations (which installed gfortran directories to the /usr/local directory. Then, whenever I try to compile anything in the terminal I get the following message:

$ gfortran -c (program)
gfortran: Internal error: Bus error (program as)

and it does not let me compile it. Please help me!! I need to fix this so I can continue my research.

if you aren't having luck I'd try Homebrew to install gfortran. You will want to remove anything your package installer created under /usr/local. It's generally safe to do so since OS X doesn't use this directory. Homebrew is a little gem of a package manager for OS X. I like it way more than Macports or Fink.