[OpenLayers-Users] XMLHttpRequest.open Error on WFS layer

[Bill Thoen]

I'm trying to get a layer of lines to open as a WFS layer and I'm 
getting this error:

uncaught exception: Permission denied to call method XMLHttpRequest.open

When I issue a GetRequest directly to the server via the browser url 
window, I get an XML file with all the expected data. But when I try to 
open it with OpenLayers I get this error and no lines show up. Does 
anyone know what's wrong and how to fix it?

The server is Mapserver 4.10.0 and I'm using OpenLayers 2.7. The 
relevant part of the script looks like this:
...
    <script type="text/javascript">
        var map;
        var wms;
        var wfs;
                
    function init() {
            map = new OpenLayers.Map( 'map' );
            map.addControl( new OpenLayers.Control.LayerSwitcher());
     
            wms = new OpenLayers.Layer.WMS (
             "States",
             "http://192.168.0.250/cgi-bin/mapserv?map=base.map",
             { layers:"us_states" }
         );
            map.addLayer( wms );

            wfs = new OpenLayers.Layer.WFS (
            "Pipes",
            "http://192.168.0.250/cgi-bin/piper_wfs",
             { typename: "ms:pipes"}
           );
          map.addLayer( wfs );
          map.setCenter( new OpenLayers.LonLat(-108.5,42.5), 7);
    }
    </script>
...

The relevant part of the MapServer WFS map file looks like this:
MAP
    SIZE 840 700
    EXTENT -125 30 -65 50
    UNITS DD
    SHAPEPATH /var/www/maps/data/
    FONTSET /var/www/maps/fonts/fonts.txt
    SYMBOLSET "/var/www/maps/symbols/symbols.txt"

    WEB
        TEMPLATE "/var/www/html/piper/test.html"
        IMAGEPATH "/var/www/html/tmp/"
        IMAGEURL "/tmp/"
        METADATA
            "wfs_title" "Piper WFS Layers"
            "wfs_onlineresource" "http://192.168.0.250/cgi-bin/mapserv?"
            "wfs_srs" "EPSG:4326"
        END
    END

    PROJECTION
        "init=epsg:4326"
    END

    LAYER
        NAME pipes
        METADATA
            "wfs_title" "pipes"
            "gml_featureid" "arc_id"
            "gml_include_items" "all"
        END
        TYPE LINE
        STATUS ON
        CONNECTIONTYPE POSTGIS
        CONNECTION "user=bthoen dbname=piper host=192.168.0.250 port=5432"
        DATA "the_geom from pipes"
        DUMP TRUE
        PROJECTION
            "init=epsg:4326"
        END
        CLASS
            NAME pipes
            COLOR 0 0 0
        END
    END
...