This is very strange. I have my laptop on mute. The mute works for almost everything (as it should), but when I get Google Talk messages, it makes a sound! I have Windows XP running on Lenovo x200. Does anyone have any idea on how to solve this?
Try this: http://www.google.com/support/talk/bin/answer.py?hlrm=nl&answer=23957. It looks like Google Talk unmutes the speakers on an incoming call.