Extrordinarily peculiar problem involving CDROM's under XP.

[BatmanNate]

Once again Windows XP has provided me with an elusive dilemma involving my hardware. Here is the breakdown: I have 2 CD-ROM's. A Pioneer 16x/40x DVD, and a TDK 24x10x40 CD/RW. Each CDROM is a master on it's own channel, both the primary and secondary on my motherboard (Tyan Tiger MP Dual Athlon, AMD 760 shipset). My boot HD is SCSI and the rest of my storage runs from a Promise Supertrak SX6000 RAID controller. Both CDROM's are set to UDMA Mode 2 under their respective IDE controllers in the device manager. Here is the kicker, though: At random (sometimes hours, sometimes months) one of the drives will switch to PIO mode for NO APPARENT REASON in the middle of whatever I'm doing. I'm clued in by that drive being particularly slow reading a disc, as in 4x slow. The only way that I have discovered to solve this problem is by switching the physical channel that the drive is on by trading the cables. The problem eventually returns however, and I'm now running XP Pro SP1. The strangest part is, when both are running in UDMA mode, the soundcard will click and pop when music or a movie is being played and both drives are copying. I think it is when this set of circumstances arises that the drive switches to PIO. The soundcard that I'm using is a Philips Seismic Edge 5.1, however it did this with my Soundblaster Live Value as well. Does anyone have a simliar set of circumstances and problems? I've been at this for quite some time and one of my buddies has the same PIO mode switching on the fly problem, and we're at a loss. And input would be greatly appreciated, thanks in advance!