Hi Matthew!
Try rebooting! I've got to reboot to get it working... be sure the plugin is CHECKED in your plugins sections of the Plus! config! The problem is also that the blue thing re-appears when you restore the contact window from the system tray; so you might try to check the option "Open messenger window ..." in the General section of the MSN options; just to be sure it works!
Good luck
- Mike
akaris@gmail.com