If it is just on pdf, it is a near certainty that they checked the Choose paper source by pdf page size option, which over-rides the print driver. I would also think that the documents themselves are probably scans of pages, that will show up as 8.5*11.01, and due to the 2 decimal places, the printer can't show you what it actually requires, because it can't do 2 decimal places in paper sizes.
So uncheck the box and try again.(the decimal point thing usually shows in the highlighter areas)
So we recently had new 7220s installed and almost everything works fine. Only thing i've noticed is that some pdf files automatically try to print from tray 5 (Bypass). The user gets prompted to load resources to tray 5, but when they do the message stays the same. We've set the default tray to tray 1, but some files still go to tray 5 and fails to recognize the paper. Any assistance would be greatly appreciated.