The problem you're having is that you're using an obselete emulator. The mist cave uses a translucent layer of white on top of all the onscreen action. A lot of emulators had a hard time doing translucency effects properly until a few years ago. A lot of the SNES emulators from that time period also had a hard time with sound. Just get a new emulator. Then again, maybe you can toggle some options. With a good program, you always have to do that anyway to get the best performance.