>I modified your suggestion slightly, trying the following:
>
>

SELECT userfile.usernumber, appfile.processid	;
>   FROM userfile 					;
>   FULL join appfile ON .t. 			;
>   LEFT JOIN accessfile 				;
>   ON userfile.usernumber = accessfile.usernumber 	;
>   AND appfile.processid  = accessfile.processid 	;
>   WHERE ISNULL(accessfile.processid) 		;
>   INTO CURSOR NewRecs

>
>Now I get error 1581, field ProcessID does not accept null values. Again, runtime only, not in development. (Actually, I'd be much happier if the errors happened in development as well, since it'd be a lot easier to try different combinations).

Check your Runtime:

* Main's start
wait windows version(0)