http://wordpress.org/extend/plugins/auto-font-resizer-plugin-for-wordpress/
I personally haven’t tested this, but it has been reported that when this plugin is active the “Add Address”, “Add Phone”, “Add Email”, “Add Social Media ID” and “Add Link” buttons do not work on the add entry form page. The cause would be that the plugin does not limit its JavaScript to its own admin pages. So if you find that these button do not work when you install Connections or that those buttons just stop working and you have this plugin installed, please deactivate it to see if it resolves the issue.