PHP function htmlentities does not support windows-1255, I believe this is Hebrew? Please check that your site is running in UTF-8. You may need to check the charset header of your Joomla template; the below example is what should be present.

Believe so, I just know Joomla should be running in UTF-8 for complete compatibility. windows-1255 is lacking support from numerous PHP function. Most cases this is defined in your template index.php when 3rd party. Default Joomla template doesn't define this at all, which means default of UTF-8 is used. You can test by switching to default Joomla template and confirming if issue still present.

The content-type should never be defined in the Joomla template directly unless using Joomla 1.x and even then it should be pulling _ISO. Joomla 1.5.x and greater adds content type automatically (valid types such as UTF-8). So removing content type from template entirely should resolve the issue unless something else is still setting the pages content type (you'd need to review source of the page you're viewing and look in the Head).