Are you sure that that's all the code you have? Because I cannot reproduce what you are getting.

    $ cat p.pl
    #!/opt/perl/bin/perl -w

    use strict;

    $ARGV [0] = $0;
    $^I = "";
    undef $/;

    while (<>) {print STDOUT "Hello\n"}

    __END__
    $ ./p.pl
    Hello
    $
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Only one time....

-- Abigail