Error on "config" plugin??

This morning, I found my omeka stated this error message :

Omeka Has Encountered an Error

Unable to resolve plugin "config"; no corresponding plugin with that name

I havent found anything installed in the plugins folder with the name "config". I got no idea waht caused this error. Need help to resolve this error.

Thanks.

Are you still having this issue?

The "plugin" referred to in the error message actually isn't an Omeka plugin. More likely, this problem is caused by not having all of Omeka's files properly installed.

Yes, it's still happens....john, could you show me on how to confirm the problem?Because I think all the neccessary omeka files are already there,in fact I have used this omeka installation since last year ...Im using a backup server for the time being...