use WWW::Mechanize;

    srand;

    my $url = 'http://avantgardeconcierge.com/';
    my $mech = WWW::Mechanize->new();
    my @a = $mech->known_agent_aliases();
    my $agent = $a[int(rand(@a))];
    $mech->agent_alias( $agent );
    $mech->get( $url );

    my $content = $mech->content();

    print "Using Agent: $agent\n";
    print "Web Content: $content\n\n";
[download]

results in the same 500 EOF response... probably because WWW::Mechanize->get() wraps the LWP's get() method.

i just tested a syscall to lynx -source $uri and it works like a champ... but i really wanted to avoid that syscall.

after looking at the resulting source code produced by lynx, i see dos-style carriage returns following all the headers returned by the avantgardeconcierge.com webserver...

it says its 'Server: Microsoft-IIS/6.0^M', but all other sites i pull source on using the exact same setup that report 'Server: Microsoft-IIS/6.0' do not have dos-style CR's as EOL markers. maybe LWP is choking on the ^M's... and thats is what produces the 500 EOF's. interesting!