The Kennedy GEDCOM is now removed, so things will be a bit easier.
I have found an error on your Manage media page. Not sure if it’s the same one you saw. It says:
0 Error occurred on in function getimagesize 1 called from line 300 of file admin_media.php
ERROR 2: Cannot modify header information – headers already sent by (output started at /home/ftprbc/alterfamily.rbcsolutions.ca/includes/functions/functions.php:341)
So you need to look at the image named A00000_A19169-21.jpg directly on your server, in the kiwitrees/data/media folder. Delete it from there if you can. Also check the kiwitrees/data/media/thumbs folder as well for file of same name.