Shoutbox

If you are using XP Pro and have Administrator privileges and are using NTFS, you can apply special permissions to StuffPlug's DLL file:

1. Locate Plus! plugin directory, i.e. Program Files\Messenger Plus! 3\Plugins
2. Enable advanced security settings control by going: Tools\Folder Options -> View\Advanced Settings -> UNCHECK "Use simple file sharing (Recommended)". Click OK.
3. Right-click on StuffPlug DLL file, select "Properties".
4. In "Security" tab, modify the permission of your sister's windows account. Generally, just deny everything and so on.
5. That way, Windows will ban any access, requested by your sister's account, to StuffPlug DLL file. And then Plus! can't load StuffPlug under your sister's windows account, for sure

If you are using XP Home, you can still do this in Safe Mode, but I don't know if they'll work perfectly though...

(The terms may be different; I'm using a Chinese Windows)