kEEP GETTING “DRIVER” ERROR IN WIN 98

Each time I boot the system I get the black and white screen right after the windows splash, telling me that “Driver for CD ROM cannot be found”. “Press any key to continue”, which I do, then it pops up one more time, so I do the same thing, then it boots fine, how can I stop this? Running Win 98. Pen lll, 128 Mb
Thanks for your time.