I suspect some web hosts are inadvertently redirecting Geo Mashup map requests with overreaching security rules.
If this is happening to you, try asking your hosting provider not to 403 redirect URLs like http://your.domain/?geo_mashup_content=render-map&map_data_key=ccae749f8b2352cccf3771da640d9759&name=global&object_id=17&map_content=global
On a page where you’re seeing this, you can copy the iframe URL as an example from source that looks like this:
<div class="gm-map"><iframe name="global" src="http://wp-svn.local/?geo_mashup_content=render-map&map_data_key=ccae749f8b2352cccf3771da640d9759&name=global&object_id=17&map_content=global" style="height: 500px; width: 100%; border: none; overflow: hidden;"></iframe></div>
