This issue has to deal with adding a Fluent UI tab according to the
procedures at: http://msdn.microsoft.com/en-us/library/aa338202.aspx

The section Im referring to is under the title: €œTo customize the Fluent
UI by using Office Open XML Formats files€œ.

This works according to article, however, if we go to Protect Workbook --
check the box next to Structure -- add a password -- save the document --
close the document -- follow the procedures in the MSDN article in order to
make modifications to the Fluent UI using Office Open XML Formats. Once you
add the .ZIP extension to the end of the file name, we get an error when
trying to open the zip file.

Title: Compressed (zipped) Folders Error
Msg: The Compressed (zipped) Folder is invalid or corrupted.

I have tried this similar case in Word 2007, but do not receive any error,
so it is particular to Excel 2007.

We are currently using Windows XP SP2 with Office 2007 Pro Plus, and I have
tried this on Windows Vista Business with Office 2007 Pro Plus to determine
if it is an OS issue, but received the same outcome so we feel it is a bug in
Excel 2007 and the MSDN article.

Thank you in advance for your attention to this possible bug in the Excel
application. Please let us know any results/fixes/questions you may have.

--
Nick