Yesterday all of our CRM servers went down and nobody was able to enter to any organization. This happened to both CRM 4.0 and CRM 2011 versions.

When a user tried to access with a web browser they got this error

 

After looking at different Blogs and forums I tried removing the servers from the domain and rejoining the domain without luck.

Also tried uninstalling the CRM product but when tried to install it back again I was not able due this same error! So I don't recommend trying this approach.

Finally the solution was installing Active Directory Domain Services Role on the CRM servers.

Restart the server after installing the role.

All the CRM servers started working back again!

Good luck!