Came across a nasty issue using rails send_data with IE. Everything worked fine until the pages were running under SSL / HTTPS. Turns out the issue is with file download over SSL when the Cache-Control and Pragma html headers are set to no-cache.
The error message from IE
Internet Explorer was unable to open this site. The requested site is either unavailable or cannot be found. Please try again later.
# before calling send_data
This issue is not restricted to rails, any server side code that sets no-cache is subject to the same issue. Glad I was able to find this post.
see also kb-316431