Simplelogin + Flash form + IE

[eluser]Unknown[/eluser]
I'm using Simplelogin to authenticate for a site I'm developing.

One section has a form built in Flash AS3 where the user can first upload an image (which works fine), then submit some text information - once that is submitted (using POST and navigateToURL in Flash) the Flash app sends the text data to a function in my CI controller to process.

At that point only in Internet Explorer (tested on 6 and 7) the session userdata gets lost and you are logged out. This works fine in Firefox and Safari.

Other forms which are not built in Flash also work fine in IE.

Any idea why this might happen?

[eluser]Unknown[/eluser]
I found the solution thanks to this post: http://ellislab.com/forums/viewthread/115220/

Just needed to set $config['sess_match_useragent']= FALSE;