Occasionally I’ll see this error pop up in the EventViewer:

Cannot get Role Manager with name <role provider>. The role manager for this process was not properly configured. You must configure the role manager in the .config file for every SharePoint process

This will occur after you have configured the Claims based authentication and tried to login to the site using Windows Authentication.  This occurs when you try to login to the site using Forms authentication then you will see above message if and only if you haven’t configured Role Manager correct. In my case I am using Sql Server Membership Provider. I have added web.config changes required for all the web applications and in the "Authentication Providers" section of the web application I have given Member ship provider and Role Manager. But, I haven’t configured Role Manager at all.

The solution will be either remove the Role Manager entry in the Authentication Providers section or configure Role Manager correctly. In my case I am not using any roles, so I removed the name from authentication providers and everything started working correct.