Note: This is different from the "Unexpected decryption error" that is stickied; though, I have re-run the downloader, and it fixed nothing.
This is on a fully-updated 64-bit Windows 7 Professional install on an Intel i5 with a Geforce 560 Ti 448 (if any of that matters -- it just might, ya never know).
On this machine I have two drives:
C: -- with less than 5.91 Gb remaining. (This is a tiny, 25Gb, system partition that I cannot free up space on)
D: -- with well over 50 Gb remaining.
I am attempting to install on D:
I have seen programs erroneously assume that C: has some certain minimum amount of space on it for unpacking setup files. Is Diablo III one of those? If not, any ideas how to fix this?