Vista - Messenger video and voice outages

Hi,

When I am on Msn Live messenger and talking to my wife at the other
end it happens a lot the webcam and voice suddenly stops. Mostly after
10 minutes or something. If we start the webcam and video again we get
sometimes an error "Live messenger is not available". But we are still
online and can use the textwindow and talk by that way.
I checked everything on my side and it looks okay. I checked
everything on my wife's computer also but the only thing I can find is
the internet upload speed is not very high. Only 14k. Can this be the
cause that Yahoo and Live Messenger stop the webcam and voice
transfer? Or else what can cause the problem.

Are there any options to change settings or something so the webcam
and voice can use the maximum of the internet speed?

Kind regards,