Hi, the private visibility "scope" of the method MetaSliderPlugin::autoload(), conflicts with other external libraries, such as in my case Doctrine ORM. Changing this to public fixed the issue but just thought I would mention it. I have a highly customized site, which I'm sure isn't the norm but none the less it seems that an autoload method should have a public scope.
Here is the specific error.
Fatal error: Call to private method MetaSliderPlugin::autoload() from context 'Doctrine\Common\ClassLoader'