The "Windows can't find one of the files in this theme" message is from the fact that ver RC3 stops windows from loading screensavers. If you have a screensaver selected in your unsaved theme and then enable RC3, then Windows won't be able to find it and start displaying this message. Two things to do: Either unload RC3, select 'No screensaver' then reload RC3, or go back to RC2 (which I did) and keep your screensaver. I can't think why this might happen, but this is what I have found so far.