Check the Login failure error from sql error log and identify the status there after.

This may help

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

http://blogs.msdn.com/b/sql_protocols/archive/2006/02/21/536201.aspx