I recently have been having the same problem that many people are having in the other thread (new contacts being blocked automatically, and other people being unable to add me).
I decided to do a complete Windows Live Essentials unistall - including deleting any 'messenger' releated files I could find on the computer.
I am now trying to re-install the program, whcih I didnt think would be hard as its such a common and well-known program.
However, the link on the Microsoft Official Website gives me a broken "webpage cannot be displayed message"
http://explore.live.com/windows-live-messenger?os=other (after pressing the 'download' button.
I have tried downloading various other WLM installation programs from other sites (FileHippo, C-Net etc.), but they all are either old versions of WLM which don't work any more, or have error messages.
(1) One of them is an old version which asks me to update by taking me to the broken link posted above.
(2) Another one starts installing, and then tells me I am not connected to the internet ("OnCatalogueResult0x8104000b"), when I clearly am.
(3) Another few tell me the installer is "not a valid win32 application"
What can I do to get WLM back?