Peter,
Thanks for your prompt reply! I've checked my preferences and these contractions aren't listed in the Symbol and text substitution list. I tried unchecking that box and still have the problem, so I assume it has to do with the spell checker suggestions.
When I do a spell check the word "could't" does not show up as being found in the spelling dictionary. Odd, since that's what it is automatically changed to.
Finally, I tried having the spell checker "unlearn" the bad spelling. When I follow the path you suggested, I don't find an "Unlearn" option. The four buttons I have are: Ignore, Learn, Find Next, and Change
Anything else I should try?
Thanks,
Mark