You can close this thread,

read the below links with the explanation of the problem and the ultimate fix.

SynAttackProtect

http://sqlblog.com/blogs/merrill_aldrich/archive/2010/06/10/windows-server-2003-network-boogey-men-every-dba-should-know.aspx

http://blogs.msdn.com/b/sql_protocols/archive/2006/04/12/574608.aspx

TCP Chimney Offload

http://support.microsoft.com/kb/942861

Query Timeout problem

http://support.microsoft.com/kb/945442

and Microsoft confirms:

SQL Server Intermittent Connectivity Issue

http://blogs.msdn.com/b/mssqlisv/archive/2008/05/27/sql-server-intermittent-connectivity-issue.aspx