ATA drive locking FreeBSD 5.4 system

[Rod Person]

I just add a 160GB ATA133 drive to my system. On this system I have an IDE DVD 
burner on IDE channel 1. The 160GB drive is on IDE channel 2. When ever I try 
to copy any data from the DVD drive to the 160GB hard drive the system locks 
up. All I can do is a hard reboot.

I have the follow sysctl in my loader.conf

hw.ata.ata_dma=1
hw.ata.atapi_dma=1
hw.ata.wc=1

I've tried to set hw.ata.wc=0 an hw.ata.ata_dma=0, but still the machine 
locks.

The machine is an older dual PIII and the IDE busses max rate is UDMA33. All 
the other drives on the system are SCSI U160 and I have no problem copying to 
the drives from the DVD drive.

Anyone have suggestions or a way around this other than only using the SCSI 
drvie to copy from the DVD?? Otherwise, It look as though I'll need a new 
machine for the ata133 drive because all my PCI slots are filled!!