Access 2003 - form in form view always opens properties sheet

Hi, I can not stop a form in form view causing the properties sheet to open whenever the form is opened for data entry use - which will be people other than me.

To explain - in an existing Access 2003 database that works correctly, I added a form that comprises 1 Form (A) using a subform (B) drawing data from 2 related tables . I used the Form Wizard to create it.

The main part of the Form A is in form view and the subform B is in Datasheet view.

The Form A works correctly and the data displays & enters correctly.

The Form A appears through a command button in the main form (C) , as do two other existing forms (D & E).

When I click the command button, the Form A opens in form view, but, it always opens the properties sheet. I have checked that Form A is set to open as default view - "single form"

The other two forms D & E open correctly in form view but DO NOT cause the properties sheet to open.

I have compared every setting in Form A properties sheet and in the code, they are the same as for Forms D & E - except of course for data source etc.

I have scoured Google for the problem, no one else seems to have come across it, or they know what to do. I am quite new to Access.

Rgds Jonathan