Hi,
Did you just replace your CDROM with a DVDROM drive?
Sometimes what happens & this is most often the case with Win98 is that when you replace a bad component(such as a bad CDROM drive or Floppy drive with another one) with a new good component, windows won't remove the original driver but will add a 2nd device driver into your Device Manager list. Then when you check Device Manager & see two components when you know you only have one, you remove the offending component & then continue on. The next time you boot or computer, you get the infamous New Hardware detected & Windows re-installs the driver for the component which isn't there. To correct this, you need to remove both of the drivers not just the one which isn't there. Then when you reboot your computer it will only find the single component.
what happens is that Windows remembers you removed the driver & thinks that it needed to be re-installed & automatically re-installs a driver which isn't needed upon reboot. Mike