Do corrupt downloads really happen these days and what causes the downloads to become corrupt? I can't remember having a single corrupt HTTP download in the past 10 years.
Yes, they do happen. Not as often as 20 years ago, but they still happen. Personally I can't download more than about 1GB without an error. If you use bittorrent you might want to look in the logs to see how often it re-downloads blocks because the block it just downloaded has been corrupted. You might be surprised.
I don't know the root cause in general, but for me the most common cause has been bugs in the TCP/IP stacks of cheap home routers.
