Try installing plus! on an account with adminprivledges..to be sure you got the one with full adminpriviledges you can boot into safemode (constantly hitting F8 on reboot, choose safemode in the menu that appears) and choose the account called "administrator".
If that doesn't solve it, you can start up plus! by rightclicking on your clock and choose taskmanager..in the menu "File" (first in the menu from the left) choose new task and browse to where plus is installed (C:\Program Files\Messenger Plus! 3) and doubleclick MsgPlus.exe..if that isn't there plus wasn't installed correctly and you need to reinstall plus on your "normal" account aswell.
Plus! still not showing in your MSN after you restart your comp (no plus! added in the menu of MSN messenger)? Start up plus! as i described above, start up MSN messenger and go to Plus > preferences > general options > miscellanious (tab) and check "force Messenger Plus! to load when computer starts"
Edit: Welcome to the forums
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