Updating of docx, xlsx or pptx files is not possible with UpdateListItems

Hi

I'm facing the same problem described here:

http://social.msdn.microsoft.com/Forums/sharepoint/en-US/c92461c8-4d09-4710-9c75-50ac68fe053b/unable-to-update-list-item-properties-with-client-object-model

I can't update docx, xlsx or pptx files in SharePoint, after I uploaded them; and I can't seem to find a reason why?!

I'm using the the UpdateListItems method from the Lists web services (with Java).

Other files can be updated without a problem.

This behavior is strange, because the SOAP return message for the docx/pptx/xlsx file is:

<ErrorCode>0x00000000</ErrorCode>

which means, the update was successful. 

Is there something special about the docx, xlsx or pptx files?? Or do I have to update them in a different way??

Thanks,

Cris