Windows Live Messenger

I am hoping someone can help. My father has an issue with Windows Live Messenger. The video is fine but the sound echo's and stutters and then the video starts to freeze up till his system crashes. I have uninstalled Live Messenger (including deleting from system registry) and re-installed, updated his sound card and video card drivers. Updated his Camera and it doesnt fix the problem.
Tried it with his firewall on and off. Yet when he uses Yahoo Messenger and it is absolutely fine (even if he is sending files or playing pool on Yahoo with his contacts).


He has

Dell 3100
Cable Broadband
Microsoft Lifecam VX3000
Logitech USB Microphone

Thank You

 

Sorry for the life of me can't see how to edit the post but....

He had no issues with Live Messenger 7.5
I have been into the audio settings and chose the USB microphone.

He managed to get in touch with Microsoft and their "assistance" was to totally uninstall XP and re-install it. I told him that was a tad drastic to solve the messenger issue.