How can I prevent "Could not apply the stored configuration for monitors"?

A quick word first: I am on the VirtualBox development team, and if this is a problem with VirtualBox I am the right person to fix it.

Often when logging into an Ubuntu guest running in VirtualBox with Guest Additions installed, I get the message "Could not apply the stored configuration for monitors" on start-up. This seems to be because Unity Settings Daemon has some specific (outdated and no longer existing) configuration saved in monitors.xml which it tries to apply. I haven't quite worked out all the details, though I note that apply_intended_configuration() ignores the advice in the documentation for apply_configuration_from_filename() to filter out GSD_RR_ERROR_NO_MATCHING_CONFIG. So the question is: what can we do about this? If there is a simple, clean change I can make to VirtualBox to avoid the problem I am fine with that (though I see in forum postings that other virtualisers have the same problem, so I am slightly doubtful). If not, can we get this fixed in Unity Settings Daemon? Preferably without my having to invest too much time into it (I am still smarting from the pain of investing hours of time to get a clear and obvious typing mistake I tracked down in the Unity source code fixed)? Please let me know what the right channel would be to talk about this.

Thank you!