I am just trying to help. Also keep in mind that i am not a TTG employee.
The reasoning behind the md5 test is, that if the files were corrupted during download once, which is implied by redownloading them fixing the freeze at one point, it could have happened all along.
That means, that the files you downloaded the second time could also be corrupted, but at different positions, fixing the initial crash, but causing one at another place.
The game checks the files consistency if you download them ingame, but using the manual download that probably is bypassed.
I had a similar case
a few years ago, and it turned out to be a defective modem.