If a non SCSI device is missing from the list, replace it.
If more than one non SCSI device is missing, isolate them one at a time until you find the device causing the failure.
NOTE: If the number of diskette drives shown on the list is incorrect, an error can occur during the tests. if this is the case, restart the computer, select View Configuration from the Set Configuration menu and verify that the drive information is correct, then continue testing.