SQL Server does not exist or access denied

I hope you will get to see the above error message most often and I say a common question among forums &amp; newsgroups. Few times you might be thinking why it is throwing error even though you are using right credentials to access that SQL Server instance. I have seen such as the basic assumption by those users getting this message believed that this is due to "Login process has failed" or "Login do not have correct permissions to connect". IN many case the second assumption is correct, as the 'access...(<a href="http://sqlserver-qa.net/blogs/tools/archive/2007/08/13/sql-server-does-not-exist-or-access-denied.aspx">read more</a>)<img src="http://sqlserver-qa.net/aggbug.aspx?PostID=1383" width="1" height="1">