IIS 7.5 HTTP Error 500.19 - Internal Server Error. Live website is functioning but has a /test url unknown to our developers which gives error 500.19

I am an intern in an interactive media company, my employers have many websites they host for small businesses. When any of the websites URL's is accessed on the web it works great, altough when you place "/test" behind the url and enter it comes up with the 500.19 internal server error, stating the configuration file path is invalid. While it should just be giving the 404 error.

We did not create the /test site. We also have URL rewrite installed and functioning but we really need to know what is causing this error. As I said it needs to give a 404 error and than perhaps we can have it rewrite this URL.

If anyone has any idea what is going on here please help. Searching the web has yielded zero results. Below I will paste the full error report.

Error Summary
HTTP Error 500.19 - Internal Server Error
The requested page cannot be accessed because the related configuration data for the page is invalid.
Detailed Error Information
Module  IIS Web Core
Notification    BeginRequest
Handler Not yet determined
Error Code  0x80070003
Config Error    Cannot read configuration file
Config File \\?\D:\Sites\vhosts\***********.com\httpdocs\test\web.config
Requested URL   http://***.*************.com:80/test
Physical Path   D:\Sites\vhosts\************.com\httpdocs\test
Logon Method    Not yet determined
Logon User  Not yet determined
Config Source
   -1: 
    0: