SQL Server :: TCP Error When Connecting To SQL Server Via User Control

We have a MOSS 2007 custom web part based on a user control that queries a database cluster. When the connection to the database is made, we regularly experience the error below and have had to create a work-around in the code to retry the connection. We have 3 environments - development, staging and production; the error only occurs in production. The difference in the production environment is it is a farm with 3 WFEs and a SQL cluster, where development and staging are single machine instances. All are MOSS 2007 & SQL Server 2008. We cannot find what is causing this issue and I'm hoping someone else has experienced a similar problem and knows the cause.

This is the error that occurs frequently when the query is executed:
System.Data.SqlClient.SqlException: A transport-level error has occurred when sending the request to the server. (provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.)
at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)
at System.Data.SqlClient.TdsParserStateObject.WriteSni()
at System.Data.SqlClient.TdsParserStateObject.ExecuteFlush()
at System.Data.SqlClient.TdsParser.TdsExecuteRPC(_SqlRPC[] rpcArray, Int32 timeout, Boolean inSchema, SqlNotificationRequest notificationRequest, TdsParserStateObject stateObj, Boolean isCommandProc)
at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async)
at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result)
at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method)
at System.Data.SqlClient.SqlCommand.ExecuteScalar()
at [Our Namespace.OurMethod](String someParam)

More than one method will generate this, but this is typical code, note the retry work-around:
public static DataTable OurMethod(string someParam) {
const string query = "sp_OurStoredProcedure";
var resultsTable = new DataTable();
var connection = new SqlConnection { ConnectionString = OurDatabaseConnection };
var command = new SqlCommand(query, connection) { CommandType = CommandType.StoredProcedure };
var dataAdapter = new SqlDataAdapter(command);
var retry = 5; SqlConnection.ClearPool(connection);
while (retry > 0) { try { command.Parameters.Clear();
command.Parameters.AddWithValue("@someParam", someParam);
connection.Open(); dataAdapter.Fill(resultsTable); retry = -1;
} catch (Exception ex) { retry--; if (retry <= 0) {
LogError("Exception: DataAccess:OurMethod: *RETRIES EXCEEDED* " + ex, "error");
} else { SqlConnection.ClearPool(connection);
LogError("Exception: DataAccess:OurMethod: ATTEMPTS REMAINING " + retry + ". " + ex, "warning");
} } finally { dataAdapter.Dispose(); command.Dispose(); connection.Dispose();
} } return resultsTable; }