You can close this thread,
read the below links with the explanation of the problem and the ultimate fix.
SynAttackProtect
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