Odd, have you attempted all these downloads from the same location (and/or connection)? How about you use an alternative link.
I've seen corporate proxy and firewalls cause all sorts of issues with downloads. Sometimes using a different internet connection, i.e your home one to download the files works fine.
Please let us know how you go. As if need be, I can download the file and push it to customer accessible ftp server for you to access.