Leaving aside all the fun new vocabulary words like "abjuration" and "lucubration" that Dungeons & Dragons players tend to pick up, there are a lot of new words in the game and related media which tend to see some disagreement in pronunciation.

"Drow" is a good example. Some rhyme it with THROW, others with COW; "ixitxachitl" is another confusing example. Monster names aren't the only stumbling blocks: I played a game with a half-orc cleric in the party who called his deity "grum-MUSH".

Are pronunciation arguments common in your games? Who do you consider the authority on these things, especially for completely (or mostly) fictional things?