Hyperlink loses reference
 

I have a workbook with multiple worksheets and several hyperlinks to cells.
For example, 'HOME' to take me back to cell A1 of 1st worksheet.
Occasionally, when I open the Workbook, Excel gives me the error 'Reference
is not Valid' for many of my links. When I hover over the cell, the path is
correct, but I have to edit the Hyperlink and input the target cell again,
then reformat the font (again). What causes this? What's the fix? Did I
mention it very annoying and time-wasting?