Connection to local SQL Server 2012 can be established from SSMS 2008 but not from SSMS 2012 I have two local SQL Server instances running on my local machine. The first is SQL Server 2008 R2 Enterprise Edition (named MSSQLSERVER) and the 2nd is SQL Server 2012 Business Intelligence Edition. 

My problem is with SSMS 2012 which can connect to distant servers but not the local 2012 instance; I can however connect to this instance from SSMS 2008.

The error message I get when trying to login is


  Login Failed. The login is from an untrusted domain and cannot be used with Windows Authentication. (Microsoft SQL Server, Error: 18452)


I must point out that I don't have the necessary privileges to access SQL Server Configuration Manager (blocked by group policy).

Any help would be appreciated.
I saw an item on Pinal Dave's blog recently that may answer your question.  He suggests adding the line 
127.0.0.1 localhost
to your hosts file

The full article can be found here

I do note, however, the situation he refers to is a machine that is not part of a domain - if your machine is, then this may not solve it