Originally Posted by
ghostface147 Uninstall and reinstall. We don't know Yahoo's internal software update schedule.
Tried that with no luck. It does it on my wife's 3GS, too.
yahoo sucks, use gmail

Huh? Gmail is not an IM application. Google has Google Talk but it stinks because there is not an app for the iPhone. You have to open the browser to go to it. That means there are not any push notifications. If they had an iPhone App I would switch to that instead.