Messinger 8.1 Cant recieve or send vdieo or use the wizzard

hey, msn works awsome but when ever i try to use the audio/video wizzard to
set the webcam up, msn locks right up. When i send a video invite it locks
up, when some one sends me a invite for there web cam msn locks up. how ever
i can send and recive files and other things just no video and or audio.

i have had this issue before in the past i would really like to know what
cuases this.
BTW i have updated all software and microsoft softwares, and even webcam
software.

thanx. Colin