Well, it looks like you solved your problem. The reason you had it in the first place is because the Geforce 4 MX isn't officially supported by PJ64 and the 1.6 plugin does some stuff that it doesn't understand very well. If you run into problems like this again, I would recommend either finding a different plugin (Glide64 + eVoodoo seems to work well for low quality hardware) or get a better graphics card that doesn't contain the letters "MX". It doesn't matter what brand, nVidia and ATi are both good (some prefer one over the other, I prefer nVidia).