Error opening xlsm file with macro button

[anna]

I have a web app that needs to:
- load an xlsm file created in Office 2010 that contains macros
- update some data on one worksheet
- stream the file back to the user

If the xlsm file contains a form button created from the developer menu in Excel, it gives the following error while opening and the buttons are stripped out:

<?xml version="1.0" encoding="UTF-8" standalone="true"?>
-<recoveryLog xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main"><logFileName>error059600_01.xml</logFileName><summary>Errors were detected in file 'C:\Project\Queries\4532.xlsm'</summary>-<repairedParts summary="Following is a list of repairs:"><repairedPart>Repaired Part: /xl/worksheets/sheet1.xml part with XML error. Catastrophic failure Line 1, column 0.</repairedPart></repairedParts></recoveryLog>

[jason]

It ought to work if you use a recent nightly release.