cd rom probs

[putnam at speakeasy.net]

I have been having trouble using my cd rom
The measage I recieve is 
cd9660: /dev/acd0: Input/Output error

I took some advice I recieved here and rebuilt the kernal I thought that maybe the problem was that the Delta Cdrom was reporting to the OS so I added the line SCSI_REPORT_GEOMETREY but when I try to build the kernal that option comes up as an error any thoughts out there
thanxs to all of you the help has been great so far.