When I create a HighMaps object, the map displays a message at the bottom with an invalid character (see red box):
This seems to render fine in all of the demos. Here is the HTML block that gets created when launched on my localhost:
<text x="426" text-anchor="end" zIndex="8" style="cursor:pointer;color:#909090;font-size:9px;fill:#909090;" y="395">
<tspan onclick="location.href="http://www.highcharts.com"" style="cursor: pointer;">Highcharts</tspan>
<tspan dx="0"> © </tspan>
<tspan onclick="location.href="http://www.naturalearthdata.com"" dx="0" style="cursor: pointer;">Natural Earth</tspan>
</text>
Try to set utf-8 encoding of your page file and set correct meta.