John, I've come upon that problem from time to time. I think it's caused by the website's using a different character encoding format than the one your computer is set for. But you can change that to accommodate other character encodings. Just go to the computer's top menu and choose View and then Character Encoding. You'll see a number of choices. I usually have mine set for Western (ISO-8859-1). But sometimes, when I get the question mark you mentioned, I just try one of the other encodings, and that usually works. I then turn it back to my usual setting once I've finished with the website in question. (FWIW, I haven't found that "auto-detect" works well for me, so I have it set to Off.)
I should add that Firefox is my default browser, and what I've said above refers to my experience with Firefox. But I think other browsers also have a character encoding setting under View--I know Opera does.
I hope this helps.