I have a spreadsheet containing 7 userforms and 9 modules. The
spreadsheet has been developed on the same computer for a number of
years and remained stable. However, I now want to make some amendments
to one of the userforms. Whenever I make any changes to the
UserForm_Initialize statement (even entering a blank space), I get the
compile error 'can't find project or library'.

Does anyone know why this happens and, more importantly, how to stop it.