Hi cainnech,
I don't have a solution, but perhaps some info from similar problems that might help. When I spool print jobs off to my z3100 directly from Adobe Photoshop via ethernet, I frequently get partial or even blank previews. If I continue to print regardless of these previews, it won't work (I can't recall at the moment if I get a partial print or simply a printer error on the front panel---it's been a while since I ran a batch). One sign something is wrong is when I look at the number of pages shown in the printer queue for that job. For me for printing photos, it should be 1 page. When I get these scrambled up print previews, the number is usually 2 or 3 pages.
My guess is I am getting a communication error of some sort while the file is transmitting to the printer. I think the communication is cut-off prematurely. Some of these files are quite large. My approach has been to cancel any print jobs that have these scrambled previews, and re-send the job to the printer. It usually works the second time. I have noticed it will take longer to send the file when it works, giving some support to my theory that the scrambled attempt was cut-off early. I have not yet pestered HP for suggestions.
I don't know if this is the same problem you are experiencing with your PDF. Does this re-submit technique help? Is the number of pages shown in the print queue for these jobs correct for the PDF file you are trying to print?
Regards,
KDJ, photographer and "1-man print shop", Ottawa, Canada.
(hp z3100ps GP 24")