You said "Nothing...in the properties." I'm assume you looked for an event
procedure (like On Got Focus or On Lost Focus) in the Events tab of the
Properties sheet for the Combo Box in question, and are not just confining
your search to the Format tab.
I still think there must be some setting (goodness knows they are plentiful)
that is responsible for the combo box behavior.
Q: Is this a regular form or is it a continuous subform?
Q: Are other controls, particularly Text Boxes behaving normally?
I assume you are aware that Alternate Back Color means "Alternating", not
"Alternative" color, i.e., for shading every other row. I haven't used this
feature, so mine are set to No Color.
Have you tried creating a new combo box (or text box) on the form just to
see how it behaves?
If you can find a control that behaves as desired, I would print out or
write down every setting you can find for it, and then compare them one by
one against the settings for the misbehaving combo boxes. If the controls
reside in different forms or sections, check the section settings as well.
I've been burned before by some little setting tucked away somewhere,
thinking it couldn't possibly have anything to do with my problem, and it
proves to be the key.
I've also been burned by putting a form into design view, changing a format
setting, then switching immediately back to form view only to find my change
was not implemented because I did not move the cursor after I made the
change, so the color (or whatever) reverted back to it's previous state
before editing.
Sorry I can't be of more help, but I'm relatively new to this.
Pew