Chances are if both drivers (CW and CD) are on the same IDE cable, that it's having problems with the wait_time between one device to another. Check under the device manager to see if the drive are in DMA or PIO-mode. If they're both in PIO, and it's on a motherboard (depending on age) that only runs ATA 33 or even 66, it may not have enough throughput to transfer data like that.
I can do CD-to-CD fine on an ATA-100 board. See if that isn't the problem.