This has
nothing to do with Messenger Plus!. Windows Live Messenger 9 comes with a feature of being logged into up to 4 places at once.
The best way to show how it works is by a diagram of some kind...
Computer 1 (signs in first)
\
\
Windows Live Server
/
/
Computer 2 (Signs in second, yet is still signed in on Computer 1)
Anything done on either PC is seen on all Computers signed into the Windows Live ID. By Default, Windows Live Messenger not only tells you that you have logged on at more than 1 location, but also gives you the computer names. Disabling this will
NOT work as it will only apply to the computer you are using.
Hope this helps