Too many "thinks" and "guesses".
First of all, you cannot save a worksheet.
You can only save a workbook which can have one or more worksheets.
A single workbook or multiple workbooks can be saved as a workspace.
Second........she goes to File>Open and selects a file from the list in the
folder but gets the message that the file cannot be found. Is this correct?
Or is she selecting a file to open from the MRU list under "File"?
If so, perhaps she has deleted, renamed or moved those files from their original
location that the MRU points to.
Gord