Can this problem be solved...

I have a list box : I need this because they can only select from the list items and not type a value in !

But some of the old records have items that are no longer in the list.
When I open the form with this record the item is not shown in the list box. I am assuming because it is not found in the list anymore.

Is there someway to show the old values yet still only allow the user select from the popup???

Thanks!