Check the size of your ISO, it is likely not the correct size. I got a similar error as the ISO was 1 Gig too small, even though Chrome said it had downloaded 100%.
If you downloaded in Chrome or Safari, you could try using Internet Explorer instead and it will prompt you to install the Download Manager.
A few people have reported problems downloading from MSDN using Chrome and Safari, and indeed downloading using the download manager solved the issue for me.
