Hi Ojster – I deduced the same as you, by trial and error, but I have also find a solution!
I found this at http://sivel.net: “The Shadowbox JS WordPress Plugin has been updated to version 2.0.4.0. More big changes in this version. Now using domready events for all javascript libraries other than ‘None’ for initialization of Shadowbox.js before the site is completely loaded………..”.
So I went into the Shadowbox settings page and changed “Javascript Library” from NONE to JSQUERY. All that does is change the “window.onload” to “jQuery(document).ready(function” – so it is now fixed! My Google map works again (http://www.craftyjo.org.uk/location-map/).
