Burner won't do UDMA anymore.

[BatmanNate]

My CD burner normally runs in UDMA mode, using less than 1-2% of the CPU's to do a burn at 24x, no chop or lag or any of that. Now, all of the sudden, it will only function in PIO mode, take 100% of one of the CPU's, and it's buffer dips so it takes longer to burn. It also chops whatever else is running, and I can't figure out what is making it do this. The burner is a TDK VeloCD 24x10x40, and I'm running WinXP Pro. I've tried both the default XP drivers and the AMD 766 ones, and both suck. I tell it to do "DMA" if available in the driver panel, yet it still loads in PIO. BUT, as in however, it was doing DMA before, and I don't know what brought this on. Thoughts, ideas?