I also had some other drives that would refuse to set itself inanyother mode that pio after a lockup in Xp.
I resolved the problem one day by just simply going to the device manager and uninstalling the drive, then do a reboot.
upon restaring windows i check again after windows got throught loading and now it had swithed itself back to Dma mode 2
For some reason when just reseting it for pio to dma would not get the job done the drive had to be uninstalled via the device manager and everything was fine after that.
Enough of my two cents.