Sound not playing on sertain programs

hi
same as title

Basicly this has been going on for a while now… i could live with it when the only programs the sound wasnt playing were ones i never used, but now i get no sound on any browser, quicktime, skype (people can hear me but i cant hear them), and probably others if i cared to look. Btw my sound card aint busted, it plays fine on itunes and wmp.

any1 got any ideas?

thanks.

edit: ive searched google with no success… but il keep looking!