Cannot upload files using multiupload using Firefox and accessing eZ publish through https.

Works correctly through unecrypted connection (http://), and also works as expected for IE8 both for http and https.

Error occurs for Firefox 3.6.3 and 3.5.2 (reported by customer).

Error occurs for both eZ Publish 4.2 and 4.3.

Error code 2038 reported in ezmultiupload.js :: function onUploadError(e) :

IOErrorEvent type="ioError" bubbles=false cancelable=false eventPhase=2 text="Error #2038"

Steps to reproduce

For eZ Publish 4.3 and english translations:

1. Connect to webserver using httpS , login to the admin interface.
2. Click "Media Library" -> right click "Images" -> select "Upload multiple files".
3. Click "Select files" button, enter "." as filename, and select one or more image files on your local disk.
4. Click "Open" button.
5. Nothing happens - the files are not uploaded.