An apostrophe character followed by a closing parenthesis character results in a spurious wink emoticon, i.e. "", and the closing parenthesis being dropped. E.g.

apostrophe (')

results in the following HTML being rendered:

apostrophe (&#039<img src="/images/icons/emoticons/wink.gif" height="20" width="20" align="absmiddle" alt="" border="0"/>

The displayed rendering looks like if the following text were entered:

apostrophe ('

This looks the same when displayed in the browser (IE 6.0) but results in the following piece of HTML:

apostrophe ('<img src="/images/icons/emoticons/wink.gif" height="20" width="20" align="absmiddle" alt="" border="0"/>

Note that the only difference is an additional semicolon here. And that's exactly what's missing in the first piece of HTML to mark the end of the entity reference. It seems like in the first case this semicolon is together with the closing parenthesis rendered as an emoticon.

With the double quote (") or greater than (>) characters, which also get rendered as entity references, this problem doesn't occur.