Recently, I upgraded my machine at work, to Windows 7. After going through the long process of installing all the essential softwares, I found that I could not get the 'Report Manager' site working. I was getting the following error over and over again.
HTTP Error 500.19 - Internal Server Error The requested page cannot be accessed because the related configuration data for the page is invalid.
HTTP Error 500.19 - Internal Server Error The requested page cannot be accessed because the related configuration data for the page is invalid.

I tried searching on google. Almost every post suggested that I should grant READ permission for the web.config file to the user group IIS_IUSRS. I did that. However, the error lingered.
Fix: Give READ permission to the user group IIS_IUSRS for the whole application.
Fix: Give READ permission to the user group IIS_IUSRS for the whole application.
- Type 'inetmgr' in the run window.
- Locate the 'ReportManager' site, right click and select 'Edit Permissions'.
- Select the Security tab in the popup window.
- Click on the 'Edit' button (to change permissions).
- Click on the 'Add' button, type IIS_IUSRS and click OK.
- Browse the site.
If that does not fix the problem, leave a comment. I will try to help.