Just a thought, to bump this along.
Your free space on the C: drive is in fact rather tight. 7% free isn't even enough room to allow Windows to defrag . (?) I'm wondering if you had more room on your C: drive if the file would render.
I understand that you are rendering to external as well as pointing your aux files there. The Studio program may still be screaming for a little bit more breathing room. Just a thought...........
Also, have you deleted your auxillary files ? Look inside the render folder and manually delete the folders from within.