At my company we developed an online learning method in Flex.
Now the following is happening.
When you link to a Word/Excel asset using Internet Explorer and your Flex app is embedded in a frameset it will open a window and close it immediately.
When using Firefox or Chrome it works fine. I also created a small test-app in Flash wich worked just fine.
Just using the regular navigateToUrl("http://www.somesite.com/document.doc", "_blank");
I guess this is a Flash Player or Flex bug?