KB Article: http://support.microsoft.com/kb/925175
You select a gallery on the Ribbon in Microsoft Office Word 2007. When you try to insert one of the elements in that gallery, Word 2007 may stop responding or close unexpectedly. Additionally, you receive the following error message:
The Office Open XML file Building Blocks.dotx cannot be opened because there are problems with the contents.
If you click OK in the error message, you may receive the following error message:
Word found unreadable content in "Building Blocks.dotx". Do you want to recover the contents of this document? If you trust the source of this document, click Yes.
If you click Yes in the error message, you may receive the following error message:
Word cannot open this document template. (drive_letter:...1033Building Blocks.dotx)