What are all possible solutions to having trouble with another user not being able to view my webcam?

I have never had any any problems with other users viewing my webcam, UNTIL now! Another user who lives on a college campus cannot view my webcam! She gets a Network error message. We have tried nearly EVERYTHING. I called Dell for support. They gave me a port number of 3422 to have opened up. I consulted Yahoo's help online. We both turned off our computer firewalls and opened up port numbers 80 (web default), 5050 and 5100 (Yahoo's assigned port numbers). She still cannot view my webcam! Again, I have never experienced this problem. Her college IT people were unable to offer additional help. This other user HAS VIEWED another person's webcam using Windows Live Messenger. I have had NO problems with users viewing my webcam using that program either. But, she can't view my webcam on that program either! If it was her college's antivirus software/firewall, she wouldn't have been able to view a webcam on Windows Live Messenger. Can I change anything with my webcam? Its USB.

There are a number of reasons why you may be having problems viewing the webcam.
Yahoo has stopped some functions from older versions of messenger if one or both of you are not on the new 8.0 version webcam viewing could be turned off.
the webcam settings should match both using either super mode or regular mode.
The new security issues to follow government restrictions says that a block of viewing webcams and a sensor in some select wording during messages passed between minor and adult should be in place. not to say you or the one you speaking to is a minor but if the age set during registration is wrong and you or the other party is seen as a minor then this could be an issue.
a minor glitch could be in stealth settings they also should match if one is invisable and the other isnt this could prevent viewing.
there is one other thing which I can think of is that internet traffic can affect this as well and if you are trying to cam during peek hours it could be affected. normally this will result in choppy viewing but at time it can through up an error and not view at all.
best of luck

w45