I have been having issues with my webcam on yahoo messenger. It was working fine, now it works for about 10 mi?

it works for 10 minutes at a time, then stops and i have to resend it. i have windows XP, the person i am sending to just got a new comp with windows 7. we have the same version of messenger, #9. the camera and old GE, but it worked fine until they got their new comp. is it a windows problem or a yahoo messenger problem? we have both uninstalled and reinstalled several versions of msg. problem is the same