Just a couple of guesses to maybe consider...
I would try new or known good Cables for your HDs...
Also, I would make sure to use the 80 wire cables, not the older 40 wire....
If you have them on the same cable, try to put them on seperate channels to see if problem goes away...
The power supply may be getting weak...
And the last idea, Overheating ? is your drives in a very hot case with little or no air flow around the drives ?
Try opening up the case so the drives run cooler...
Just a few Ideas that come to mind when I hear this problem...
Hope one helps.....
SeeYa
