Is your printer USB perhaps?
Ages past when I used W98SE and had several SCSI items, a SCSI scanner was the joker in the pack.
Regardless of what Windows was telling me, the answer was to install the software first.
When next booting and from there onwards Windows would ask for the software and I pressed Cancel!
It only got the message when I went through the wizard and let Windows search (fruitlessly) for drivers for the "device"and right through to finish.
Although the scanner worked fine, and no message reappeared, whenever the scanner was in use a quick look in Device Manager showed the yellow triangle.... a sort of sulky YahBoo to me.