Try saving your scene just before you batch render. Seems to be a bug in 2011 or at least it is for me. I have autosave on if it autosaves the scene batch render never works untill I manually save the scene and try again.
Dave 
--EDIT--
Sorry i see you already tried that. Best of luck if you work it out let me know. Batch rendering in 2011 has been buggy as hell for me even under SP1
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