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):
Code
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?