I think you have problems with the old Aspi-Layer integrated in Win 98.
Download a new Aspi-Layer from Adaptec.
The Aspi is easy to Install,add a Adaptec Controller in the Hardwaremanager to your System.(I know you don`t have one,but the Installer needs one)
After Install of the Controller,start the new Aspi and after it tells you everything is ok,delete the Controller from your System and reboot.Thats all.
Or take a look in the Internet for the Program
Force-Aspi it has a cracked installer.