Very weird, unless something else changes in the cr2 in the process... You can edit a cr2 in a text editor, try to open it in WordPad (or something similar) and edit the obj path entries by hand. The easiest way is to do a search for the old path name throughout the document and just edit in the new path. Save the new cr2 with a new name, or work on a copy to be safe. This way you can be absolutely sure that nothing else is changed in the cr2.