What tilly and Fastolfe have said is correct. I have seen this also happen with certain web servers and file associations.

For example, your web server may be configured to invoke files ending in .pl or .cgi with 'perl.exe'. If possible, you may be able to add the -T flag to the association, set a TaintMode directive in the server configuration file, or write a wrapper batch or shell file that calls the interpreter with the right flags and passes the script name on to it.

(I also like the use diagnostics; pragma instead of perldiag, when I'm really confused by something.)