Error messages
When an error message (which includes error "0 Ok" which means that no error happened!) BASin will pop up an Error Dialog which contains the error, along with a short explanation of why it might have happened. Clicking the Okay button will hide the dialog, and return you to the editor. The Continue button will issue a CONTINUE codeword as a Direct Command and resume program execution if possible.
You can turn this behaviour off with the checkbox at the bottom of the Error Dialog or by using the relevant Options page.