Webcam not working

When I am on Yahoo Instant Messenger and someone send me an invitation to
view their webcam, I cannot. It says I am behind a firewall and can't view
them. I use Zone Alarm Security Suite but turned it off as well as Windows
Firewall but it still won't let me view. I never had this problem before I go
this new computer with Widnows Vista and I was using Zone Alarm with Widows
XP before and all worked find.
Can anyone help?
Thanks

The drivers don't work with windows vista get a new webcam or look for new
drivers

You may not understand my question. I cannot view the other party's webcams
when they invite me to view them. When I turn on MY webcam, they can view me,
I just can't view them.