Audio trouble

Hello,

I am having trouble with the my audio I can hear whom ever I am talking to but they cant hear me cause of hella interference. I did not have this problem before downloading the msn messenger 9.0. Is anyone else experiencing this problem? If so how can I fix this? By the way I have a done the audio ajustments in messenger, works fine then, but acts up only when I am talking with some one

Thanks for your time
Siobhan