This morning we suddenly can't connect to our sql server 2008 developer edition. I have try with both of Windows Integration mode and SQL Authentication mode. Both are failed. It complained the error: "Login failed for user ''. (Microsoft SQL Server, Error: 18456)". I'm sure that it works well with the same usernames before. I haven't do any broken changes on the operating system or sql server before. I can't find any useful clue from Windows Events. In the article http://blogs.msdn.com/b/sql_protocols/archive/2006/02/21/536201.aspx, it said that we may have more details from the sql server log. But, now, I even log into the server. Do you have any idea? Thanks.
Leo