An attempt has been made to edit a .PROGRAM or AUTO statement while the program appears on some task execution stack. While a task is on a stack its subroutine arguments and automatic variable values are kept on the stack. Changes to these statements modify the stack which is not allowed. Remove the program from the stack by allowing the task to run until the desired program executes a RETURN instruction or issue a KILL monitor command to clear the stack. If you are using the SEE program editor press the Undo key to allow you to continue editing.