The Google Maps API is constantly changing–they say they are releasing weekly. Of course, no one is perfect, so sometimes bugs appear. First, you should read this about maps API updates:
The v parameter within the http://maps.google.com/maps?file=api&v=2 URL refers to the version number of the Google Maps API to use. Most users of the API will want to use the current “Version 2” API by passing the v=2 parameter within that URL. You may instead obtain the latest release (including the latest features) by passing v=2.x instead. However, be aware that the latest release may not be as reliable as the v=2 release. We update the Google Maps API often (sometimes every week), at which point features within the v=2.x release are migrated into the v=2 release unless problems are discovered.