I wanted to add ...
I went ahead and logged into Yahoo! through IE, downloaded and installed Yahoo! Messenger, and it connected just fine...
So, I logged off, and uninstalled Yahoo! Messenger immediately.
(due to the fact Trillian uses 11MB of resources and Yahoo! Messenger uses 54MB)
screenshot:
http://i58.photobucket.com/albums/g2...y/yahoobad.jpg