- access the CMS over https using IE8. You can use Woonsan's excellent reverse proxy script  for https testing on a local environment.
Reproduction path using the demo project:
- open the site
- in the menu select 'persistence'
- fill in the form and click submit
- open the cms
- navigate to the easy forms export perspective
- use the tree to load a persisted form in the 'export view'
- click the checkbox of the persisted form
- click on 'Download as CSV'
- a CSV export file is downloaded by the browser
- IE8 shows an error dialog with the message: "Unable to open this Internet site. The requested site is either unavailable or cannot be found. please try again later."
More info here  and here