openlayers 2 - WMS GetMap MIME type error

After adding the following to the top of my index.html page

I begin to receive the following error on my GetMap WMS request

    Resource interpreted as Image but transferred with MIME type application/vnd.ogc.se_xml

Any thoughts on why this would occur are appreciated. Here are the URL params of my WMS request:

    BBOX=-15130249.425402,2538320.1060898,-5869750.5745982,6461679.8939102
    FORMAT=image/png
    HEIGHT=802

    LAYERS=EFETAC-NASA_1YrBaseline_previous1
    MAXEXTENT=NaN,,,
    PROJECTION=EPSG:900913
    REQUEST=GetMap
    SERVICE=WMS
    SRS=EPSG:900913
    STYLES=
    TRANSPARENT=true
    UNITS=m
    VERSION=1.1.1

    WIDTH=1893