First, Qimage does not show the Print Preview when it is selected, but only with this paper
It is not Qimage that is not showing the Print Preview, Q has nothing to do with it once it's finished its processing, it's the driver
Are you printing over a network by an chance, I believe that can cause odd problems like preview not showing?
Pleased to hear that you got a good print on the new paper but if plain paer did not feed properly, maybe there's an intermittent fault with the printer.
Hopefully some other 3800 users available to comment on your problem here.
Terry.