We had a really irritating problem today. We upgraded a workstation to a 64 bit version of Windows 7 and reinstalled everything. All fine except for the HP Officejet K8600 printer which refused to print anything larger than A4, no matter what settings we changed in the driver.
After a lot of troubleshooting and some research, here's the solution.
Head into the Properties for the printer. (Control Panel > Devices and Printers. Right click on the K8600 and select 'Printer Properties'.
Click the 'Advanced' tab.
Click 'Print Processor'
Select 'winprint' from the list in the Print Processor box and leave RAW selected from the list in the Default Data Type box.
Click Apply, click OK and close the Print Processor window.
Restart the machine for good measure and try again.
Hope this helps somebody!