IF you’ve installed Yahoo Messenger in your Computer through Online installer instead of offline Installer you should know that Yahoo Messenger installs Yahoo AutoUpdater service in your Computer which checks for Messenger updates and notifies you about the same. As a result you’ll see YahooAUService.exe process running in Task Manager (this process won’t appears Yahoo Messenger installed offline).
Disabling YahooAUService.exe or uninstalling Yahoo AutoUpdater
To disable this process from running in your Task Manager, you need to uninstall Yahoo AutoUpdater component installed in your Computer.
For that navigate to “C:\Program Files\Yahoo\SoftwareUpdate” directory and double click on Uninst_AutoUpdate and click on Uninstall button, Yahoo software Update will be uninstalled and this process won’t appears from now on in your task manager.