RTD.RefreshData crashes when invoked from modal form

I have created a very simple modal form with two buttons: one just closes the form, and the other calls Application.RTD.RefreshData. In Excel 2003 this all works just fine, but in Excel 2010 the Application.RTD.RefreshData crashes with

Run-time error '1004': Application-defined or object-defined error

If I create the form as modeless everything works fine in both Excel 2003 and Excel 2010.

For what it's worth, this is all the code behind the form:

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And I invoke the form using this code in my sheet:

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Is this a known issue with Excel 2010, or am I really not allowed to call Application.RTD.RefreshData from a modal form?

EDIT:
I should add that as far as I can tell I have no RTD servers in the Excel session.

EDIT2:
This workbook demonstrates the problem. Would be very grateful if anyone could confirm whether they see the same issue, and in which version of Excel...
RTD simplest.xls

Hi a.collister

Welcome to the Forum!!

Code does not error in Excel 2003 or Excel 2007
Run Time Error in Excel 2010...no clue why...