Interesting. I always use the preview, and as you mention, I have noticed it happen when sitting idle with the preview waiting for the ok to print. But it happens I think as much with sending off within secondss. I can send again and it works a couple times. Other times I shut the printer off and back on.
Sine I have to always define the paper size it with non ps, I get confused on the way QImage or LR makes the orientation. The preview assures me. I was thinking to soon move to w8. I wonder what this is? Is you ip static?
Maybe I should try USB, but then I think I lose another function, or something happens, right? :-)