The stability problems could well be your RAM -- very, very few PC100 sticks will work *reliably* at 133. I can boot up at 933 with my old PC100 ram, but Prime95 torture test starts having round-off errors after a few minutes! My RAM has Micron 8ns chips; it worked stably for weeks at a time when I was overclocking my p3-450 at 124MHz (within the 8ns spec), but it doesn't seem 100% reliable at 133.
On another note, I also think I got a dud cb0 -- I can run 124MHz at 1.70v but I have to hit 1.90v to do 933!!! (1.85 is about 99% stable, but I still get some random crashes.)