Old hardware (HP IIP Plus) and Win98 question

Here I am at the frontiers of modern technology.

I dug my old HP Laserjet IIP Plus printer out of the basement, hooked it up to the printer port on my nifty SMC router, running from my Win98 system. Note that everything I describe below happens when the printer is directly connected to the computer also.

The thing prints fine, and I’ve got enough toner to last me until the Great Thaw of 2007. But every time I fire up the computer, I get an error message “53 ERROR” on the printer. The book says that this is a memory parity error of some kind, but I think the book lies.

If I disconnect the printer cable, and then turn on the printer, everything is fine. I then hook up the cable and I’m off to the races. If I turn on the printer first (while the computer is off), then everything is fine.

I only get this problem when I turn on the printer after I turn on the computer. I vaguely remember that I had this problem a few years ago, which is why I retired the Laserjet in he first place.

Obviously, having such an aged configuration I can’t get help through the regular channels, so I’m placing my trust in the Teeming Millions.

Anyone got a fix? Anyone got an idea? Is there some registry setting I can tweak? All help appreciated.
Scruff