If you get this error, this article may apply. If you're accessing your Teaming Site with secure connection (https) and you receive an error while opening a document (Word,Excel, PDF, etc) that indicates
"Internet Explorer cannot download....."
"Internet Explorer was not able to open this Internet Site. The requested site is either unavailable or cannot be found. Please try again later"

See Microsoft KB "Internet Explorer Cannot Download" Error Message When You Use an HTTPS URL to Open an Office Document or PDF File

This basically says, if you utilize the security feature "Do Not Save Encrypted Pages to Disk" in Internet Explorer, and you use https to access a site, you could experience an issue opening certain documents. This occurs when you click on a thumbnail view to open a document in a File Folder. You can Right-Click and open in a new window without a problem and you can right click and save. The Edit or the HTML link works fine as well.

If you access the site using standard http, this error does not occur.