The problem is the Helvetica font. Eunoia uses Helvetica (or Neue Helvetica) as the default website font and in your case the Helvetica font is broken.
Three solutions:
1) Install a proper Helvetica font pack on your windows pc. Make sure that you remove all "old" Helvetica fonts first.ยด
2) Uninstall all Helvetica fonts. Your Win PC will then use Arial.
3) Add following code to custom.css:
.main_menu ul:first-child > li > a{
font-family: Arial, "HelveticaNeue", "Helvetica Neue", Helvetica, Verdana, sans-serif;
}
.widgettitle, .miniheading, .author_name, #reply-title, #top .logged-in-as, .dynamic-column-title{
font: 10px/17px Arial, "HelveticaNeue", "Helvetica Neue", Helvetica, sans-serif;
}
#top #wrap_all .big_button{
font: 12px/40px Arial, "HelveticaNeue", "Helvetica Neue", Helvetica, sans-serif;
body {
font: 13px/1.65em Arial, "HelveticaNeue", "Helvetica Neue", Helvetica, sans-serif;
The css code will replace the "default" Helvetica font with Arial. Macs will still use Helvetica because they don't have Arial installed.