I was currently working on some integration tasks between SharePoint 2013 online and CRM 2011 online. Here we wanted to use one of the search pages configured in SharePoint 2013 online inside an iframe of Case form in CRM 2011 online.
SharePoint 2013 online and CRM 2011 online were part of different Office 365 domain. After specifying the url for the iframe we got the following error
Found the following kb article
Then tried hosting the SharePoint 2010 online search page that is part of same domain in which CRM 2011 online is. That worked properly.
Hope it helps.