Hmm is not cause vista x64, i give you my word cause i install msg plus live 4.7 on it and run without any error, but there was an option i remember i saw once that allows you to show or not the msg plus icons in the toolbar, so i just wanted to ask you if you can use plus features such as colours in your nick and sounds... maybe is just off the option that shows the icons
check if you have the plus menu o.o