Hmm ... can you check Main_1.pak and Main_2.pak too please?
These are mine (just checked, they unpack OK with 0.1.12d):
Main.pak 830761ba8a6103147e58e9b77fb4d6bc26e50cc8 1,080,590,336 bytes
Main_1.pak b396b6ba160eddb304894675a53a825c86829ac4 1,073,741,824 bytes
Main_2.pak f4e99db776d67044b124eb9e9217fa8ce1bfe1f5 147,423,232 bytes
Also, does unpacking fail at the very beginning, or does it progress a bit before failing?
Fails immediately.
SHA and Size: Size matched, comparing your SHA to mine, same.
b396b6ba160eddb304894675a53a825c86829ac4
b396b6ba160eddb304894675a53a825c86829ac4
f4e99db776d67044b124eb9e9217fa8ce1bfe1f5
f4e99db776d67044b124eb9e9217fa8ce1bfe1f5
This is two units. One I've done all my work on, the other the only thing I've done was copy over the Mod I use for coop into \Public\. Neither cannot unpack Main, same immediate error.