Facebook iframe not working in IE; session/login issue?

[Vargstid]

I have an issue with my Facebook canvas iframe application.I'm using sessions to build a simple questionnaire-style application. There's a question on each page, when the form is submitted the answer is stored in a session array, and the page number is incremented by one, which then displays the next question. Simple stuff.This app, however; works in every browser except Internet Explorer.In Internet Explorer, on page change it appears to go through another page change which invalidates the session, and starts all over again. I've searched and searched, but can't seem to find the course of this behaviour.I've placed the source code of the app at http://gist.github.com/613083. The app is using the standard PHP SDK provided by Facebook at http://www.github.com/facebook/php-sdk.