Problems with gta iv?

okay so i have the ps3 and started playing gta iv. for the most part it was fine but today all of a sudden some wierd **** happend. none of the voices of the characters play and i know this because i have subtitles on and none come up when the characters are supposed to be having an in-game convo. also when i drive the cars the radio just sounds like im switching through stations and i cant hear the engine of any car i drive...wtf is going on