If Flash movie CS4/AS3 is added with Wicket/Ajax then AS3/ExternalInterface.call
Suggestion is that wicket-ajax.js:268 (1.4.1) breaks IE+Flash/ExternalInterface:
// place all newly created elements before the old element
while(tempParent.childNodes.length > 0)
This "removeChild" breaks Flash/ExternalInterface in IE. If "removeChild" is removed then everything works fine.