>xbap doesn't support full trust.
>
>>You need to go into the application Properties, go to the security settings and set it to "This is a full trust application."
>>
>>I haven't played with XBAPs but you will have to deal with the full trust issue when you go to publish it as well.

So it let's you set it to full trust for development, but not for release?

Once I switched his project over full trust it was able to run a win form in the browser.