Gillbot - How many sticks of RAM do you have installed? I had a P3V4X with a single stick of PC133 128MB CAS3 (SPD) Micron RAM. It would run fine at 2-2-2, but when I tried ot enable 4-way interleaving, I got the same thing as you. However, when I popped a second stick in, they both worked just fine in 2-2-2 mode with 4-way. Have you tried changing your settings to 3-2-2 or 3-2-3 or some other "half-way" combination?
-Aaron