Our piwik runs behind a ssl reversed proxy.
Trying to export csv files (under the widgets and on the api page) failes in Internet Explorer 8.
Browser Error Message is something like "Could not download index.php ...".
So I think the headers are wrong.
We already set the reverse_proxy setting to 1 in global.ini.php.
Can you test if other export formats are affected?
CSV, TSV and JSON are affected.
XML and PHP do work.
(In ) refs #1793 - refactoring output() to renderHeader()