Reason may be that the server of the page you want to view does not send the right encoding with the header.
You can force the browser to use a special encoding instead of "automatic".

In the Browser go to "Ansicht"->"Codierung"->try
utf-8 (or an onther encoding the site may want to use)

My interface is German so maybe yours says "View"->"Pagecencoding"

Niko