YQII wrote...
As always with things like this, the problem could be on both ends. Do you have a slow internet connection, or do you share it with someone else? My old student net used to dip immensely during peak hours in the evening, which would lead to downloads stopping in the middle and ending up corrupted like you describe.
I just downloaded the PDF and ZIP myself, so it sounds like a temporary load issue—on our servers or your net. I would also simply suggest trying again at a later time, preferably on numerous occasions during off-peak hours.
I have gigabit fiber to my house so it wouldn't be that it is because of peak useage times, like cable/dsl would be.