can not hear conversations in the movie

hi, i downloaded some mives. video works fine. and the background sound is great too. but i can not hear conversations in the movie. anyone knows how to solve the problem? many thanks.

I am having the same problem I have AC3 filter and such, but the volume of the voices in all the movies I download have this problem. The age of the movie or when it was ripped does not make any diffrence ether.
Could some one please help us with this problem?