i keep hearing this really annoying sound (something like a thick every 30 sec) and it only happens when i use msn, i've removed and reinstalled my msn windows live messenger several times, with and without add ons  but i still hearing this... suggestions?

Have you disabled the WLM's Sounds, on "Opitions"???
If no, go on Opition > Alerts and Sounds > Look at the list and disable them...

Note that you can hear the sound by clicking a little "play button" down the list: just select an event and click on "Play Button"