Query based on combo box: Error 2118 - You must save field before requery action

I have a subform that is based on a query which looks to the value in the combo box.  

Combo Box OnChange event contains subform.requery method

The combo box on the subform from a column in the underlying record source.  When I select a value in the combo box, the requery method works perfect and just displays those records which meet the criteria in the combo box.

When I clear the combo box (by deleting the data), and the requery method tries to execute (on change event), I get the following error:

'Run-time error 2118'
You must save the current field before you run the Requery Action.

If I halt out of code and the press "F9", the record source displays all the records.

Is there any workaround to this bug/problem?

Thank you for your help.

P.S.  Interesting Note:  I put a button on the subform to set the combo box = null and then execute the requery, and everything works fine.  The problem lies wherein I delete the data from the combo box using the Delete Key, the on change event is triggered, and the subform is requeried....  That is when I get the above error.