Non-keyboard chars in string left/right of Holidays Symbol
Cause : Q++ has noticed non-keyboard characters in the Surround Symbol By setting of the Holidays (Display) property of the current DiaryGridLine. Non-keyboard characters are ASCII characters that have no visual interpretation, such as #0 (the null terminator character).
The only possible exception that will work correctly is the use of the em-dash. But even so, you should use the corresponding invisible character token, &m, instead of this character.
Consequences : Remove these characters, or Q++ may crash during diary generation. At best, your output file will look strange as QuarkXPress may not be able to deal with some of these characters.
•Edit the problem string : Automatically opens the property editor so you can correct the string that generated this message (it will be easy to spot as some charcters will be replaced by black squares or other weird characters).