I've seen this work from time to time so I'd give it a shot.
Go to Start -> Settings -> Control Panel -> Add/Remove Hardware -> Uninstall or Unplug -> Uninstall -> Check mark show hidden devices.
Clear out all the devices on the secondary channel, then remove the secondary channel, and then reset.
If you see duplicates of hardware in the list remove them (like your CD-ROM twice). Also there is always one "? Unknown Device" in that Add/Remove Hardware list. Do not remove it. You won't like what it does. If you have more than one "? Unknown Device" leave the very first one alone, and remove all that follow.
The Add/Remove Hardware panel is not the most well thought out tool, leave Control Panel open, as you will have to enter the tool after the removal of every device and you may only remove one device at a time.
The tool works great, whoever designed how the interface operates should be slapped though.
Once you are back into Windows after having removed the devices, you should see that all the devices on the secondary channel are in PIO again. Shift the drop down menu to DMA if available and then reset.
Sometimes the value in the registry that reports DMA compliance for the channel gets goofed. Clearing out the channel and devices will sometimes help.
If it still doesn't work you may be experiencing either a system BIOS bug or a drive based firmware bug.
Updating either may help. If you do update the system BIOS, drive firmware, or both though, you'll have to follow my instructions on device removal before you will be able to see the results of the BIOS/firmware updates.
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