The 80071392 error is caused due multiple Windows Live Messengers running in the background, even if you don't see them appearing in the taskbar.
To fix error, simply run Task Manager by pressing ctrl+alt+del buttons or right mouse click at Taskbar and Start Task Manager. End all processes that contain msnmsgr.exe or anything very similar to this if you are using an older version of Messenger.
Once you end Msn applications you should be able to run and sign in to Messenger.
If for some reason you still can't get ride of this error I recommend you to run top registry fix tool, Registry Easy to fix and speed up your Windows.
