Getting back to Chuck's original subject, I sometimes get the problem, and sometimes all is OK. With IE8, looked at one post just now where an apostrophe showed as a little "character unrecognised" square. Out of curiosity, I switched to Firefox, where the apostrophe looked OK. Weird, as Chuck said. Seems to show up on the following characters:
UKP sign £
and maybe quotation marks " colon : and semicolon :
I'll see how those turn out when posted; they look OK as I type.
Edit: they all look OK, apart from the UKP sign in IE8. It's really odd that, as I add this to the message in IE8, the UKP sign above looks fine in the text pane, but I bet it disappears once I post this edited version.
Never mind, the missing symbol can usually be deduced from the context.