Have a Vista machine that was working fine and then stopped printing. Would not see printer. Uninstalled the HP software and then Vista would not let me reinstall. Vista detects when printer is plugged in (USB) and when I point it to the HP cdrom I get an error thats not the correct driver. Vista shows it has a MS driver for the printer model and when its selected I get an error that its not digitally signed. I see Error 6161 in event log for printing. Attempted a system restore to a few days before printing stopped which did a successful restore but machine still will not print and will not let me reinstall driver.