It is strange. Chez, did you turn over the print, say foot first printed instead of head of the image? The 82" is within length limits I know so that question should not be asked either but nevertheless. One way or another, part of the printerdata is lost. No white area cut settings done in the driver? I always keep the standard setting in the PCL3 driver. What does the HP preview show? If you open the spooler window, do you see different sizes for the printer data for the same job? If that all shows no flaws then the issue is beyond the driver and in the transfer to or storage on the printer.
Ernst, op de lei getypt.