The problem is that you are using an older version of Google maps which used images we used to host, but have taken down.
The solution is to either download and use the more recent version, which should fix this problem, or to manually update your google maps .js file.
It has:
icon.image = 'http://google.webassist.com/google/markers/traditionalpillow/poppy.png';
icon.shadow = 'http://google.webassist.com/google/markers/traditionalpillow/shadow.png';
icon.iconSize = new GSize(34,35);
icon.shadowSize = new GSize(34,35);
icon.iconAnchor = new GPoint(9,23);
icon.infoWindowAnchor = new GPoint(19,0);
icon.printImage = 'http://google.webassist.com/google/markers/traditionalpillow/poppy.gif';
icon.mozPrintImage = 'http://google.webassist.com/google/markers/traditionalpillow/poppy_mozprint.png';
icon.printShadow = 'http://google.webassist.com/google/markers/traditionalpillow/shadow.gif';
icon.transparent = 'http://google.webassist.com/google/markers/traditionalpillow/poppy_transparent.png';
You would have to update those paths to the paths to the images you want to use.
