How Do I reset DMA?

I am using Windows XP Pro on my dell dimension 2400 desktop. When I try to burn a disc from my LG DVD-rw drive it keeps getting slower. I went to my computer and right clicked on properties. I then clicked the hardware tab, then device manager. I found my drive which is the secondary IDE channel. I then double click on it, and click on advanced settings. My drive is under the device 0 tab, where the transfer mode is DMA if available, but it keeps kicking it back to PIO mode. How do I keep it on DMA, and out of PIO mode. When it is on PIO mode, my burner runs very slow. Is there a way to set this secondary IDE channel where the DMA is the default, and how can I reset the DMA, so that my burner can run at its full potential? Can Someone please help??