Error in creating feed (strange characters?)

I have the plugin installed and a feed at http://drottninggatans.se/?em_ess=1

There’s something wrong with the feed however:

This page contains the following errors:
error on line 279 at column 93: Entity 'Atilde' not defined

Is this something I can solve or is unsolvable except for the developers?

http://wordpress.org/plugins/events-manager-ess/