As far as I can see, the question marks appear on Firefox wherever an “em dash” (–) should be. (On IE they are small boxes, and on Opera question marks inside a diamond.) This basically suggests that the character there is for one reason or another something that these browsers can’t display.
I don’t know why, though. Have you modified your template files?
Ok I see what you mean. I modified some stuffs about plugins and I confess that I think (but I’m not sure) that it didn’t appear like that before…
Some thing in your stack is not utf-8 friendly. Check your Apache configuration to make sure that utf-8 character set is supported and set properly.
Thanks. I found that it was the fault of my PHP editor, Namo, which changed the file in a bad way. I then edited with Wordpad and everything works great now!