This looks like a user-edited Resource.xml that's out of date.
Make sure you don't have anything in [Media Center Install Path]\Data\Custom Resources.
Thanks but actually it wasn't there! It was in C:\Users\Erik\AppData\Local\VirtualStore\Program Files (x86)\J River\Media Center 14\Data\Default Resources
This seems more like a bug? Why would JRiver write stuff there?
Erik.