Shouldn't it be like this? I'm not sure if the initialize is required since it's not being used.
code:
function OnEvent_Initialize(MessengerStart)
{
}
function OnEvent_ContactSignin(Email)
{
if (Email == "*******@hotmail.com" && Messenger.MyPersonalMessage == "Nukkumassa")
MsgPlus.PlaySound ("C:\\Documents and Settings\\Tomi\\Omat tiedostot\\Messenger äänet\\happytreefriendsthemesong.mp3") ;
}