If you have a file with the extension on all upper case letters, clicking in the "edit in office" will not work at all.

Steps to reproduce:

1. Create a page and add two attachments.
2. Add two attachments in there:
   
3. Click in "edit in office" for the DOC2.DOC.
4. Nothing will happen.

Note: This is not reproducible in IE and it was tested against the latest version of Fire Fox (28).

Expected behaviour:

The file should open normally as the second file, doc.doc.

Work Around

Change the file extension from upper case (DOC) to lower (doc).