Windows Service Pack 2.0 and "SQL SERVER does not exist or access denied" problem

We got a series problem with our SQL Server(which is in a seperate windows 2003 server in our subnet) after  installing Windows Service 2.0.
The problem was that our application sometimes could and sometimes could not connect to SQL Server. That was really shaky and we should refresh the browser several times until a successfull connection stablished. 
We all convicted the Windows Service Pack 2.0 but disabling its firewall has no effect and the problem persist. None of us could not imagine that all problems may caued by SQL Server.
Yes, The culprit was SQL Server with no Service Pack on it  and the Windows SP2 was wrongfully accused!!!
Installing SP3a resolved the problem and there is not more "SQL Server does not exist or access denied" also we enjoy Windows Firewall enabled.

So before convicting anyone check the version of your SQL Server and make sure the it has the latest service packs.

To identify the version of SQL Server and its service pack use the following script:

SELECT @@VERSION
GO

For more Information:

http://vyaskn.tripod.com/sqlsps.htm
http://support.microsoft.com/default.aspx?scid=kb;en-us;q321185