Plugin Section Auto Suggesting to use System Plugin

Hello Everyone,
This problem is kind of weird and i just checked recently that in the plug in section of my blog, there was a must use section where it’s suggesting me to use “System Plugin” which i searched a lot in the wordpress directory but didn’t find any plugin in that name. Also there is message showing me “Files in the /wp-content/mu-plugins directory are executed automatically ” . In the description section, there is showing Version 3.7.1 . I think it’s suggesting me to use the system plugin version 3.7.1 . I think may be i deleted some important plugin and that’s why its showing me this. Any help in this matter would be much appreciated. Please reply me as soon as possible. Also i am having some problems recently, may be its because of this , problems like posts not loading, getting error and after several times of reload, it’s working again. And this problem only happening when i am working as an admin.