Autoexpand does not work

In my database (Access2003 SP3) I have a combo box, which has a query as row
source. This query gets its values from a table with the fields id and
field1. Field1 is shown in the box, the key column is hidden. Autoexpand and
Limit to List is on.

After closing of the database and reopening, autoexpand does not work any
longer. After having made changes of the query forward and back again,
autoexpand may work again, but only until the database has been shut down
once.

Can anybody help?
TureB