Popups like this appeared recently in the map windows – even if the user claims to use Google Chrome! The reason is the internal use of Microsoft’s Internet Explorer control which sometimes isn’t liked very well by Google.
Messages like these appeared in the past as well as the complete denial of map scripts. This usually happens when Mixcrosoft or Google do some “optimizing” updates in the beckground. We always found a workaround so far, and you can keep calm: just click on “Close” and the maps will work as expected.