Word 2007 – In use error when saving document

Regardless if it is an existing file or a document just created, as soon as this user tries to save the document she gets an in use error. It is only in Word and doesn’t appear to matter which file format. If she browses to the directory where she was trying to save the file, there is a blank document there by that name. It doesn’t matter if she saves to the desktop or to the network, and no one else has reported this issue. Any ideas?