No sound with iTunes7

Okay, I know there has been a lot of questions about itunes 7 having a distorted playback and having problems with the gapless playback and whatnot, but I'm having a different problem. Gapless playback went all the way without itunes freezing and instead of hearing distorted sound, I hear no sound, but the interface says that the song is playing. I know my system volume is on and that my speakers work because if I use any other media player, I hear the song, it is like this with every song in my library. iTunes 6.whatever worked great, but now I get nothing. I've looked through all the iTunes settings as well.
Any suggestions?
Thanks
EDIT Again: Quicktime videos will play in the iTunes with sound, mpg and so on will not, I don't use the aac audio or whichever format itunes uses, so I don't know if those song would work, but mp3 appearently wont