Just an FYI. Seems that you may be experiencing problems chatting with your friends who are on Yahoo's IM network.
Yahoo to Trillian: Talk to the hand
http://zdnet.com.com/2100-1104_2-5245821.html
Beginning at about 6 p.m. Wednesday, Yahoo changed its instant messaging language to prevent third-party services, such as Trillian, from accessing its service. Like previous statements, the company said the block is meant as a pre-emptive measure against spammers from its Yahoo Messenger service.
Users fume over Yahoo-Trillian scuffle
http://zdnet.com.com/2100-1104_2-5246933.html