HTTP Error 500.19 - Internal Server Error ( messed IIS )

I've looked on some of the same questions around here but couldn't find what i need. I think i messed up my IIS 7.5 ( and i don't even know how - only thing that comes to my mind is that maybe i uninstalled something but i don't remember ). A while back all was working perfectly and now not even an empty site doesn't work anymore. I just get the 500.19 internal error for every one.

Example:

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 0x80070005

Config Error Cannot read configuration file due to insufficient permissions

Config File \?\C:\Users\stalker\Desktop\BDI\Proiect\web.config

Requested URL http://localhost:80/Proiect/Default.aspx

Physical Path C:\Users\stalker\Desktop\BDI\Proiect\Default.aspx

Logon Method Not yet determined

Logon User Not yet determined

Config Source -1: 0:

web.config file for the site

<configuration>
    <system.web>
        <compilation debug="true" targetFramework="4.0"/>
    </system.web>
</configuration>

This site was tested on another computer and worked. As all my other site applications. I'm thinking of reinstalling it >.< but maybe you can offer another solution.

Looks like the question has been asked and answered previously on SO... https://stackoverflow.com/questions/5615296/cannot-read-configuration-file-due-to-insufficient-permissions