I downloaded the stackoverflow.com-PostHistory.7z file from here and I can't extract the 7z file. I tried 7-zip software and WinRAR. I also tried extracting from 2 different hard drives. Both failed.
I got the following error in 7-zip when I tried to extract:
Data error (cyclic redundancy check).
The error appeared after about 50% of extraction like in this picture:
<sha1>c51c4886f7477365fa1a687b1c3e04b4bd6c96ac</sha1>which you can compare with the hashes that you generate for your local file. If they differ you know your local bytes are incorrect.