Resolving "The linked document cannot be found in the view" errors

As I have mentioned countless times before, Lotus Notes’ error messages are not always the easiest to understand. So, too with this one. A user called me over, complaining that she’d get this error whenever she opened any documents in her own mailfile.
 
After a lot of trial and error, I found that the error lay with the mailfile design. However, replacing it was not enough; you actually have to replace it with a different design, close the mailfile, open ot, then replace it with the correct one again.