How to resolve my Yahoo Instant Messenger?

Over the course of a couple weeks my Yahoo Instant Messenger has been acting up, but tonight it reached a new level of frustration, As I was typing today, my computer decided to disable me from communicating with every person on my messenger list. Whenever someone buzzes me or tries to type a message, it will acknowledge that they are typing (for example it may say, Lindsey is typing a message on my end) but once they press enter the message will not show on my side of the screen, just as if i were to press enter my message won't show on my side of the screen. However, both my and the other person's comments will show up on their message box. Then as if it couldn't get any worse whenever they try to call my computer I can accept the call, I can hear what they are saying but now it won't let them read what I type. Please if you have had any experience with this sort of problem your input is appreciated. Thank You.