I tested your plugin on my local development environmental after exporting my live website db.
I cannot access my custom post types, e..g localhost/mcm/audio-custom-post-type/ archive. I have checked my taxonmoy and CPT settings no problem.
If I disable your plugin everything works 100% again.
Does anybody else get this?
My local development setup as PHP5.4 not 5.3 as my live that is pretty much the only difference.