Is there a timeout on the connection made by URLLoader.load? If there is, what's its value, where is it documented and can it be changed? Also, what event (if any) gets dispatched if the timeout occurs? Is there a difference between AIR and browser application in those regard?
Answer is here.
Update The timeout comes from the system proxy settings. On Windows (I don't know which OS you are using) it's the same settings that IE has, which can be modified here.