I know I didn't start seeing this until Access 2007. Insomuch that if you alter the underlying query of a combo box and you don't press save a bajillion times as you close things back to your form it probably won't save. ... forget trying to copy and paste them if on the same form and you might just lucky on different forms (if they are unbound). I really dislike '07 and having to build combo boxes each time.
I was thinking I read about some patch somewhere that was supposed to fix this, but I lost the link to the read ... maybe someone else has heard the same?
-dK