For some reason, my extensions are all screwed up. The multi-user login won't come up when I start the computer, therefore it goes straight into my account. Then, on all of my extensions, it will say something like "System Extension This extension adds functionality to your computer. To use it, place in the extensions folder and restart your computer." But it's sitting right there IN the extensions folder! Can anyone help? Also, I'm missing my Apple audio extension for some reason.