it's not really normal, but it can happen sometimes, especially with a bad sound card. What is yours ?
You should try to turn on "advanced options" in the "Misc Options" menu, and then try the different parameter for the sound fx in the "Audio" menu. Try 8 bits instead of 16, 44khz or 11khz instead of 22.
ManuTOO == Mana Games == >> I don't answer Private Message, except if it's really a _Private_ topic <<