Additional data:

The error log shows: Error 18456 Severity 14 State 38

According to this site

http://sqlblog.com/blogs/aaron_bertrand/archive/2011/01/14/sql-server-v-next-denali-additional-states-for-error-18456.aspx

error state 38 indicates:

"The database specified in the connection string, or selected in the Options > Connection Properties tab of the SSMS connection dialog, is no longer valid or online (it might be set to AutoClose or the user may simply not have permission)"

This is not the case in my setup. Database is valid, is online, permissions are set to the group.

Any data anyone?