I've got an option button that is clicked to indicate a newsletter subscription. I want to grayout the newsletter expiration box if this option button is not selected.???

Well I think if I understand your question this is what you would have to do.
enter this code:

Private Sub optionbuttonname_Click()

If optionbuttonname.value = true then
newsletterdatebox.enabled =false
Else newletterdatebox.enabled = true
End sub

optionbuttonname is your option buttons name
and where newsletterdatebox is you should enter the name of your newsletter expiration box.

just reply if you need more clarification,
Rpb