Hello !
I encountered the same problem. I am French, and I fear that all the infos you gave on this topic can not help, as I have only one messenger running when I start it (Windows Live Plus! Messenger), and the biggest problem I encounter is the following one : I have three accounts, one is @hotmail.com, the others are @hotmail.fr, and the one with @hotmail.com doesn't connect, just as one of the two others, and only one gets to connect. Isn't this strange ? Why does only one account of three connect ?
And more strange : I can connect on my @hotmail.com account from another computer, but only not on mine ! I can access to my mails, I managed to connect on webmessenger, but only not on my computer !
I obviously removed messenger from my computer and reinstalled it, but nothing to do, it still doesn't work...
Please help me, because I found no help on French forums or online help sites, this error message seems to be unknown down here, I don't understand why...
Thank you for your answer, hoping you will be able to help
Bye,
Seb.