Yes, I suspect you are right about the save file being corrupted, probably while trying to save to a disk with not enough space on it. I just started a new game and that solved them problem.
I looked up the log file, and it has about 45 lines of generic looking messages involving buffers and files, then these two lines:
Graphics.CopyTexture can only copy between same texture format groups (OpenGL internal formats: src=35905, blockSize=3 ; dst=32856, blockSize=4)
(Filename: Line: 1384)
Over and over and over for 15gb, lol.