When you get Plus! to work then do the following.
Open MSN > Click the Plus! Menu > Click Preferences > Under General Options Click Miscellaneous > Check the last two boxes. (Options are below)
Display recovery window when Plus! menu is not active
Force Messenger Plus! to load when computer starts
Still dont work, try uninstall Plus! and remove all settings and reinstall it.
I think I have found the problem - I use Adaware Pro, it I believe was asking for a registry update to be changed for MESS + but was blocking the update.