Open your form in design mode and make sure the Properties window is open. ("View" -> "Properties")
Select the combo box. Then look at the "Data" tab in the "Properties" window.
RowSource will be a SELECT statement. For this example, will assume a Contact database...
SELECT ContactID, ContactName from tblContact
BoundColumn: 1 (This is ContactID, the first column in the SELECT statement)
Now select the "Format" tab in the "Properties" window.
ColumnCount: 2 (Matches number of columns in the SELECT statement, ContactID, ContactName)
ColumnWidths: 0";1.5" (zero length column is "hidden")
Richard