MenuBars(xlWorksheet).Reset causes 50290 Run Time Error in Excel 2013

[PoggiPJ]

Due to a mixed 2003, 2007, 2010, 2013 environment, we have postponed modifying the ribbon, and instead use the menubar to provide our users with application specific menu options. This worked without incident, until one of our users upgraded from Excel 2007 to Excel 2013 Office Professional Plus. Now when he runs the application he receives...

Run-time Error '50290'
Application-defined or object-defined error

The code is pretty simple.

Private Sub Workbook_Deactivate()
'Reset any prior menu bar changes
    MenuBars(xlWorksheet).Reset
End Sub

I've asked the user to compare references but have not yet heard back. I will also ask if he completely un-installed the old MS Office prior to installing 2013.
Any other thoughts would be much appreciated.