Typographers Quotes are Document Specific settings.
You need to make sure that any previous documents are set to Typographers Quotes by manually selecting them in the Preferences.
To make it stick to All New Documents, change the preference with no documents open.
Hope that helps.
Thanks very much Eugene. Any idea what might have caused this to become unchecked in the first place? I'm the only person working on my computer. I do work on files between my mac laptop at home and my mac at work quite a bit, but all are on cs5.
Well the Toggle for this in the Keyboard Short Cuts is Shift+Ctrl+Alt+'
That could have done it.
You should go to Edit>Keyboard Shortcuts
Product Area: Text and Tables
Go to Toggle Typography Quotes (press T for a shortcut in the shortcut panel neato)
And remove the shortcut.
Ah-HAH! You are a wizard. Thanks so much!