I'm also experiencing problems with auto save. It's like the connection is lost, even though my connection is just fine. I can't use the buttons for saving, previewing or publishing after it went into auto save mode. Only option would be to temporarily disable auto save via wp-config but that's not really a nice solution. Could this be a problem with AJAX? It's showing in all browsers on all systems (as far I tested). Could someone look into that? Much appreciated!