Does anybody have a permanent fix for the 'enter parameter value" dialog box
that pops up after closing my query dialog form.
I have gone back and looked at my query, the record source of my combo box.  
I even used some code that will set the recordsource value of the combo box
to null, just before the DCmd.Close command.  I just can't get this thing to
stop.
I also tried the suggestions on microsoft's website.  Been working on this
for a week, and it's starting to become a pain to solve.

Scenario - Select a report from my reports menu, Custom Query Dialog form
appears: {combo box, two command buttons( Open/Close)
Problem happens when I click on the close button.

Record source of combo box. - SELECT tblSopNumbers.ControlNumber FROM
tblSopNumbers;

SQL Code for query that report is based on -

SELECT tblTraining.EmployeeID, tblSopNumbers.ControlNumber,
tblTraining.Training_Validation, tblTraining.TrainingDate
FROM tblTraining INNER JOIN tblSopNumbers ON tblTraining.ControlNumber =
tblSopNumbers.ControlNumber
WHERE (((tblSopNumbers.ControlNumber)=[Forms]![frmTraining Summary By
SOP]![cboSop]) AND ((tblTraining.Training_Validation)='Yes'));