Let her do the following:
- Activate the Visual Basic Editor (Alt+F11).
- Select Tools > Options...
- Activate the General tab of the Options dialog.
- In the Error Trapping section, select 'Break in Class Module'.
- Click OK.
Then run a macro. The Debug button in the error message, that is disabled in the screenshot that you posted, should now be enabled, hopefully.
Let her click Debug.
This should take her to the line of code that causes the error - it will be highlighted in yellow.
Does that provide a clue?