Field can not be modified?
This seems unusual. I have (had) a script that presents a Custom Dialog with three "input" fields. Actually only one of them can accept input. The other two are calc fields and are there as information. However, the third field, on any layout, CAN be modified except via the Custom Dialog. It's a creation date with modification allowed. It tracks when a tax number has been created. On rare occasions this date must be back-dated. I've solved the problem by dispensing with the Dialog and having the script go to a layout where the change can be made. However I'm very curious why this should have happened in the first place.