Windows -> Run -> Regedit
[HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows Live>Messenger]
Create a new DWORD name it [MultipleInstances] values set to 1
Restart MSN or Live Messenger
Windows -> Run -> Regedit
[HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows Live>Messenger]
Create a new DWORD name it [MultipleInstances] values set to 1
Restart MSN or Live Messenger