Google Maps Place Marker becomes un-clickable after certain zoom level

Have a large number of place markers that are loaded in through a couple of KML files. The KML is created from a PHP scri开发者_StackOverflow社区pt but the rest of the controls are all done through JavaScript. Up until a certain zoom level (appears to always correspond to half-way on the zoom control) there is an InfoWindow that loads whenever they are clicked. However, after that half-way zoom level the markers become unresponsive. Have been unsuccessful at figuring out any reason for this behaviour.