I've started to have a look through your files. So far, I' haven't found the problem.
But I've notice the strange "behaviour" of the software when unpacking the pack.dat file. It could be due to the amount of files in it (quite numerous actually ). But that's just a guess.
Edit: Is your game running fine without the BreUnor animations? I'm asking because I've spotted some differences between your entries in the descr_skeleton file and the original one from the Myth.