At what stage of bootup does it print this "zero"? Immediately after POST, at the DOS level, or once you're in W98? What happens if you hit <F8> and boot to Command prompt only, do you still get it?
You don't say what make or model of printer, but maybe check for an updated printer driver? Check any settings/dip switches on the printer (if it has that facility) to ensure they're correctly set.
And more importantly, does it print a test page, and your docs ok?
ROGER - GØAOZ.