Can you run it from the command line? If you haven't yet done so, get the ActiveState compiler -- using the CGI module, you can run your scripts from the command line and simulate working in a browser environment.

I suspect you probably want to do something like: print "Content-type: text/html\n\n"; before you print anything else to the browser, as you'll definitely get the "500 Internal Error message" without it. The appropriate subroutine in CGI.pm is header(). If that fails, see My CGI script runs from the command line but not the browser. (500 Server Error).