Swashplate,
I use all Fast SCSI-2 devices (2 X Seagate HDDs, Plextor 8X CD-ROM, Iomega Jaz drive via a PCI host adapter (Adaptec 2940 I think) and never a glitch at all. Using old Pentium 233Mhz, Windows 95b with IE5.5 and it hums along merrily.
Suggest looking in control panel, system , device manager and see if the properties of the CD-ROM are valid, if you can refresh, or else remove and re-install. Also look for updated drivers. Failing that, see if you can borrow another SCSI CD-ROM drive from a friend and try it. Another idea is to try a Buslogic host adapter. SCSI is great when it works well but it will keep you busier than a one-armed man with five barrels of snakes and only four lids when it misbehaves!
Also check cables and especially the crimped-on plug that goes into the rear of the CD-ROM unit for any damage.
Hope this is useful.