When does this 'high noise' occur? WavePad doesn't do anything with your soundcard or its output, and as the problem continues even after WavePad was uninstalled I doubt that this was the cause. It might be that there is a loose connection somewhere in your system, or that the particular song (or whatever) you were playing was corrupted in some way. Computers don't just make noise by themselves, typically a program will need to be playing the audio for it to appear on your soundcard.
