I have a user with Windows XP Pro and Excel 2007. Whenever she opens a spreadsheet, makes some changes, she tries to do a Save As and save overtop of the previous/existing file. She receives an error '<filname>.xls may have been changed by another user since you last saved it. In that case, what do you want to do? ' and prompts to Save a Copy or Overwrite changes.
I am positive no other user is changing the file when this occurs. It is only happening for the 1 user, no one else is experiencing this. If she just does a File > Save, it saves without error.
What could be causing this error and how do I fix it?