I seem to remember having the same issue with my BlizzardPPC060 and graphics card with p96, I think it was being caused my an env variable, possible either related to loading graphics into fast ran or enabling 44KHz audio over the onboard audio chip or possibly both.
As my A1200 Tower and BlizzardPPC card are in storage I cant test that just at the moment. But It may be worth checking the amiga guide help file for p96.
Or you can just stick with CyberGraphiX which seemed to be quite good when I had my BlizzardVision , but I needed to swap over to p96 when I got my Voodoo3 card, and that's when the real problems started trying to play WHDLoad games.
