I'm assuming you open the SWF in the standalone Flash Player when that happens, right?
If so: the reason lies within the fact that a random parameter is automatically added to the URL to the XML every time (in this case the ?r=707068) to circumvent Flash's caching - which oftentimes keeps things in cache even though they're in need for an update. The standalone Flash Player does not understand that parameter syntax (it's an http/browser thingy), so it actually tries to open a file with that name - which doesn't exist, obviously.
I'll have to investigate how to tell whether the engine is running inside a browser or the standalone player, then I can add a workaround for that.