My buddy at work figured it out, the renderView had apparently been uparented or deleted. So he found this bit of code to fix it:
CODE
//Takes care of a STOOPID Maya error where the renderView object goes MIA
string $renderPanel;
string $renderPanels[] = getPanel -scriptType "renderWindowPanel"
;
if(size($renderPanels)) {
$renderPanel = $renderPanels[0];
}else{
$renderPanel = scriptedPanel -type "renderWindowPanel" -unParent renderView
;
scriptedPanel -e -label "Render View" $renderPanel;
}
//
Then the image writing part was changed to:
CODE
//Renders the Thumbnail...
render
-x $thumbnailSize
-y $thumbnailSize
$thumbnailCameraName;
renderWindowEditor -edit -writeImage ($destinationFolder + $poseName + ".bmp") $renderPanel;
//
Thanks Anyway!