Same kind of error occurs trying to 'Erase filex' where filex is in use elsewhere, namely the OS ( first saw it on NT over 3 years ago ).

Work around is UDF with low-level I/O to FOPEN() / FCLOSE() prior to 'Copy' or 'Erase'. If the FOPEN() is successful, then you should FCLOSE() and then do the desired command -- the OS passes errors to the VFP handler for the low level I/O and then you can see those errors in your code.