Thank you, Charles! I did try even that, but it didn't work. I checked the disc and there they were: 01, 02, 03, 04, 05, 06, 07 (but the order was still different: 01, 03, 04, 05, 06, 07, 02). The only explanation in my case seems to be that 02 was added to the folder later than the others. So I tried to copy each file to another dir in the correct order, but to no avail. Nr 02 is very large, the largest of them all.