Custom Ribbon shows shortly, then disappears

[hbrems]

I'm trying to display a custom ribbon when a form is open using the Ribbon Name property of the form.

The ribbon is saved in the 'USysRibbons' table. I have verified that the Ribbon XML is correct. In fact here it is:

<customUI xmlns="http://schemas.microsoft.com/office/2006/01/customui">
    <ribbon startFromScratch="true">
        <tabs>
            <!-- FORMS -->
            <tab id="tabForms" label="Forms" visible="true">
                <!-- EDIT -->
                <group id="groupEdit" label="Edit">
                    <control idMso="Cut" label="Cut" enabled="true" />
                    <control idMso="Copy" label="Copy" enabled="true" />
                    <control idMso="Paste" label="Paste" enabled="true" />
                </group>
            </tab>
        </tabs>
    </ribbon>
</customUI>

When I open the form I can see the ribbon appear for a split second and then it disappears again. No error messages are showing.

Does anyone know what's causing this (I'm using Office 2007)?

 

[hbrems]

The issue seems to be that my form is a popup form...